WordPress + WooCommerce, PrestaShop and Magento already do that. Drop $10 to $20/month on hosting on DigitalOcean, install Wordpress, install WooCommerce, buy a cheap theme, buy whatever extra plugins you need, setup your payment system (PayPal and Stripe are supported), and you're off to the races.
And it's better than that, there's people with years and years of experience in modifying and creating plugins and themes so once you have enough $$$ from the basic setup, re-invest into the business and get better developer support for all the GPL'd plugins and themes you're using.
So all the average person needs to set up shop is design skills, software engineering skills, understanding of servers and PII, and the time to do complete all technical tasks while also building up their actual product catalogue.
That's a lot, and goes a long way in explaining why Shopify has a justified usecase.
First, shopify is like $30 for a month. I'm $30 for a few minutes. The cost savings are laughably huge. And shopify's better anyway! Their plugin ecosystem is great, the admin tools are built specifically for merchant admin types (as opposed to boil-the-ocean blog admin UI with merchant UI hacked on top of it), so my cofounder/brother, who handled listing and fulfillment and that sort of thing, had a much easier time with it.
Shopify could literally 10x their price and it would still be a great deal. And this is for a lifestyle-sized biz. few $k/mo in transactions. For anyone doing this "for real", it's a rounding error.
Their plugin and theming is a joy on the dev side as well. Great docs, easy to get a sandbox account, theming in Liquid is a joy for anyone who's done jinja/handlebars/etc, their default themes have beautifully documented CSS.
I would, as the developer, literally pay my own money for shopify to be part of the stack just to abstract all that crap away from me. The time savings for me alone justify it.
I'm currently converting a homegrown multi-million dollar eccommerce platform to Shopify and it's been a dream. Most of the significant lifting was done in less than 2 weeks.
Their graphql api has just been amazing, not to mention all the other developer services they provide.
OFC, I do feel like I'm coding myself out of a job, as I've spent the last 7 years building and maintaining that system.
And now I'm switching it all to shopify plus with no regrets. I learned a hell of a lot coding my own ecommerce platform, and would love to work for a company like Shopify.
Long term we are thinking Ship Station or maybe ZenDesks ecommerce offering.
Disclaimer: I work for ShipHero.
Shopify is a hair more expensive than some competing processors, but when I last dealt with it, they were in league of paypal, stripe, square, etc, so it wasn't a differentiating factor for us, and I suspect that's true for most businesses of our size.
I get that using stripe or paypal it's easier sometimes, but for woocoomerce and alikes you usually have plugins already developed to use other payment platforms.
If Shopify means they hire this guy for a tenth of the time, they save $9000.
They would have to be moving 300k/mo for hiring a full time to even break even.
In any case you can do what everyone else does, bake the fee into your prices and call it a day - it's not like you can compete with Amazon on the low-prices front anyways.
Is this satire?
Hey now, stop with the name-calling :P I work on and use proprietary end to end solutions for ecommerce (but not Shopify).
Woocommerce wins for me because it lowers development costs and costs are lower overall. My perspective is definitely someone who has developed ecommerce sites, not solely as a non-technical user, and for me it's very advantageous to lower costs by using and modifying GPL'd plugins and themes.
I guess Shopify has 4000 employees and enough cash and enough direction to come out of box with a good UX and good defaults and that's good enough for nontechnical users.
Amusingly, grasping that concept was a big factor in my decision to put my MBA degree on hold...
An example of how it could apply is if shopify were to "go down" often thus driving your customers to your competitors that roll their own solution that has good uptime.
Even for technical users / developers, their time is better spent than fiddling around with 10 different tools.
This might or might not be true. Fiddling with 10 different tools often gives you are much larger level of control. If you need some control that you get with 10 different tools that the single source doesn't do then you are stuck with 10 tools. The downside of course if you now need to fiddle with 10 different tools.
Make the correct decision for your situation.
I guess I wasn't clear enough in making my point: Wordpress + Woocommerce can be setup very quickly and with minimal fuss and they can be as heavily customized as you want and rival whatever plugin-heavy Shopify sites are out there.
Seems like a pretty obvious choice for a small business.
But it's light-years ahead of WordPress+Woocom.
Neither of these are well set to run a proper ecommerce without heavy customizations though.
My wife is starting a fashion business. This is a hill too high to climb for a non-technical user. She was up and running in 30 minutes with my credit card and Shopify earlier this week. We don't have time to maintain an instance, troubleshoot Wordpress theme and plugin incompatibilities, etc. That's time better spent on sales funnel optimizations, manufacturing product, and customer support.
Would we consider more advanced ecommerce systems? Sure, when she hits $1MM/year in annual revenue. Until then, Shopify earns their keep (and margin) by taking care of the mundane. Make dollars, don't pinch pennies.
See: "Dropbox is just ftp + git" 
* Until then, Shopify earns their keep (and margin)*
That's fair. For business stuff I've swiped the credit card and paid for support as well. If the Shopify experience is easier than WooCommerce, etc. then I get it.
But she hated the web-based admin interface and it was way too cumbersome to get anything customized, products added, etc. In the end it just wasn't worth it and she's now on Weebly. Shopify and Weebly have their own faults and can definitely be a pain if you want to do anything off the beaten path, but for the non-technical user who just wants to sell things I see the value over a self-hosted Wordpress install.
Just set up 10-20 warehouses, hire a few hundred workers, train them, get an HR rep, IT, finance, and support, and you're off to the races!
Kids are so lazy these days, with their long hair and their rock'n'roll music.
For someone at the beginning of their ecommerce journey, Shopify is the BEST way to start making money almost immediately.
And there may be a split between the most successful and least successful customers of Shopify, but Shopify gets to make money off both.