That is not true.Most cars nowadays seem to have so much electronics controlling their operation that there's precious little you need to know or can do apart from how to check and top up the various fluids, check and adjust the tyre pressures, have the car serviced once a year, and call the breakdown service.
Well your average Joe can fiddle with their car, fuck it up 'cause they're clueless, and then pay to have it fixed. Known plently of people done that. You are obviously not your average Joe. Classic cars are also a lot simpler to understand and work on.