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.