Robots are the excuse, not the reason. The fact is, a robot is cheaper than a $15/hour burger-flipping employee, but it's also cheaper than a $7.50/hour employee, so the automation is practically inevitable. All the robot 'cost savings' are coming regardless, and fewer people will be employed (or they'll change employment to something else).
The only reason to keep wages low is to save money on the salary costs of jobs where a robot can't replace a human. Arguing that wages shouldn't go up for those people who robots won't replace only serves to protect profits and income for the people at the top.
I think the idea is that $7.25/hr is already that point.
Let's say that each of these robots costs $10k per year, including R&D and maintenance. Let's also say that because of inefficiencies with having people order their own food or with assembly ultimately being done by hand, a store has to install 6 robots to replace 3 workers.
So it is actually less expensive already to replace minimum-wage workers with robots. The minimum-wage issue has very little to do with it besides trying to keep wages low in general.
A blogger created a calculator that allows you to determine (over a 5-year time frame) whether it is cheaper to buy an expensive robot and do automation or to just use manual labor and to save the excess in Treasury bonds. He found that when the minimum wage is at $7.25, it would be slightly cheaper to hire humans, and if the minimum wage is raised to $10.10, then it would be slightly cheaper to hire robots.
The blogger assumes that it would cost $150,000 to build the robot, including R&D and maintenance. This comes out to $30,000 per year (while your assumptions claim that the bots only cost $20,000 per year to replace one human).
I'm thinking specifically in the case of McDonalds and other large chains where the costs of R&D and dedicated maintenance staff would be spread over thousands of restaurants.
You're forgetting Onion2k's point that it's cheaper for companies to hire robot-replacable employees because it loweres the wages of the non-robot-replaceable labor. Under that theory, the reason they can't bring in the robots is that their remaining labor costs would increase.
Personally, I don't know why that would be, given that companies pay what they need to get employees to work there and nothing about the NRR's job would change if the robots came in.
Even if the robot costs more today, that wouldn't change the inevitability of it happening. A $10k robot this year will be a $5k (in today's value) robot in 5 years. While wages go up, tech costs go down. No one will escape that.
Per the above: Momentum Machines says your average fast food joint spends $135,000 a year on burger line cooks. Employees work in a chaotic kitchen environment that necessitates no-slip shoes in addition to the standard hairnets and aprons.
That $135K figure should give some perspective on the if/when question.
I look forward to an entirely robotic fast-food joint. Drive up, wave your rfid card, get a list of your last 5 menu choices, poke at one, food comes out the slot in a bag. No human involved.
Restaurant means different things to different people. To me, I do not care if a fast food establishment (McDonald's, Qdoba, Panera, etc...) replaces workers with robots. The food and experience already feels autonomous and disconnected.
I do not see robots replacing servers at non-fast food places for a long time if ever.
They bring up grocery stores but I think most employees, especially check out clerks, will be replaced by machines. As much as I love to talk to the older person about their grandkids while they, slowly, scan my items I would be OK with dumping my items onto a tray and having the machine do all the work. Almost like self checkout except for a robot replacing me.
Robots are comming to restaurants regardless. There is already touch kiosks where you can order in some restaurants, there is one at a Panera Bread near me, and many in some airports.
The only reason to keep wages low is to save money on the salary costs of jobs where a robot can't replace a human. Arguing that wages shouldn't go up for those people who robots won't replace only serves to protect profits and income for the people at the top.