You are kidding, right? Cars have hardly changed at all, still the same petrol powered devices with are a hard shell. Sure the car companies were forced to add in some extra safety mechanisms, but this does not mean much.
What? That's so wrong it's not even funny any more. If you look at the advances in efficiency (on all fronts - energy consumption, manufacturing, maintenance, ...), comfort, safety and basically all facets of personal transportation, it's nothing short of amazing. Today you can buy a new car for 4 months middle class wages and it'll be miles beyond anything you could buy just 25 years ago. (ok maybe not counting some things like leather seats, but apart from a few exceptions like that).
How often do cars break down now compared to 30, 50 or 80 years ago? I am pretty sure most of the early drivers were quite good mechanics, these days? Not so much. I'm sure Mr. Ford would find modern cars very foreign.
A chair, clothing and even houses haven't changed much over the years either. Most designs only change bits at a time, slowly morphing into unrecognisable things.
True, but a minor head overhaul would have been about 1/2 an hour with 'roadside tools' (say to replace a valve spring) possibly during your trip to grandma.
Today that same repair would be a couple of days in the shop, requiring tens of thousands of dollars of specialty tools. Of course those springs don't fail as often as they did back then (a combination of improved materials science and engineering) but when they do the fix is out of reach, even for a trained mechanic without access to a shop with all the required specialty tools.
I don't think anybody carries a valve spring compressor in their toolbox. Plus you'd run the risk of dropping the valve unless you was really careful and good luck getting the keepers back in on the side of the road without a way to hold the valve up. Even then who has the parts with them to make this a 1/2 hour job? Cars are just as hard/easy to fix now as back then. Fuel injection is arguably easier to troubleshoot then a carb given the computers help.