Physics is physics.
The prop is no more than a screw which screws itself into the air around it, and the variable pitch mechanism is the gearbox
So a plane isn't going to magically do 10,000,000 miles while a car would do only 200,000 miles, on the same kind of propulsion device technology.
Right. Which is why a piston aero engine has already fulfilled more than it's share of work when it comes time for an overhaul, compared to an auto engine.
If the auto engine gets overhauled (or more often junked) at 200,000 miles, then the aircraft engine which goes to 240,000 miles, gets overhauled, and then flies another 240,000 miles, is doing quite well.
Each of my cars, including my current Dodge Grand Caravan, have been over 200,000 miles. My Caravan, which just went over that last month, is on it's fourth transmission.
Then again, the engines on some of the airplanes I'm flying have well past 25,000 hours on them.
I think aircraft piston engines do quite well. There's certainly room for improvement, but with such a small market (and it is small), putting the money into development and certification is somewhat of a losing proposition, to say nothing of product liability.