Compare it to early cars, where every operator had to know a bunch of stuff about it just to keep it running, but it was simple enough that the average operator could learn that stuff.
Are you really going back to early cars here? I mean, I think we can break it into basically three eras. The early age of cars was characterized by horseless carriages. The prior age of cars was ushered in around the 1930s or 1940s, where automatic transmissions appeared, the control layout became standard, and vehicles were pretty much all fully enclosed unless they were specifically designed to be a cabriolet. And the modern age of cars came with the O2 sensor, and self-tuning.
For the earliest cars, it was common to hire a driver and mechanic, because keeping the car moving was a full-time job. Maybe halfway through the period it became reasonable for people to maintain their own vehicles, as the reliability came up to the level where you didn't have to be an engineer to keep it going.
Obviously, the middle era was the time when any schmoe with a set of wrenches could fix a car. There was very limited availability of fluids, so vehicles were engineered to use what was ubiquitous, which was all the same. Vehicles were easy to maintain because they wasted a lot of space. On the other hand, reliability was nowhere.
Most modern cars are staggeringly reliable, but maintenance is a mixed bag. Oil changes tend to remain trivial, but transmission oil changes may be a massive PITA. You have to get the car flat and level and add fluid from the bottom while running on a disturbing percentage of modern vehicles, and there is no dipstick. A radiator flush is exactly as hard as it ever was, and you install a flush tee the same as ever. The battery, on the other hand, might be in the wheel well behind the plastic inner fender. Even if it's someplace supposedly convenient like the trunk, it might be a PITA to get in and out as it is in my A8. And you have to jump start from the battery, too. There's no redundant terminal under the hood. That would have just added weight and crap so they skipped it. The starter takes power from beneath the frame rail on the right side, you can apply power there if you have to but again, what a PITA. On the other hand, even reasonable estimates of the service intervals are all much longer than cars from the prior era. And on the gripping hand, nobody is meant to own cars like that for more than half a decade or so. They are for rich fucks who can afford to turn them over :)