Being someone who has had over 20 service visits in 20 months of ownership, I couldn't disagree with you more. Many of the issues I've had have no relation to how the car is driven. I don't want to get into a long list here, but things like wipers, chargers, battery heaters, cooling fans, and the variety of creaks and sounds that have come from various parts of my car have nothing to do with my driving. The only thing that I *do* do is that I drive a lot. 25k miles per year. Much of that is highway driving, so if by driving habits you mean driving on the highway a lot, then perhaps my driving habits are contributing to my issues, but if you're implying that I'm somehow abusing my car or driving it "rough", you couldn't be further from the truth. I take very good care of my car.
That said, I think a bigger contributor to number of issues found (and relevant to this thread) is the threshold at which someone considers something a problem. While I've had several issues that have actually caused alerts and errors on the car and needed parts to be replaced to ensure my car doesn't break down, several of the issues were related to how much you're willing to live with a certain hum or sound or noise that some part of the car makes. I'll admit I'm probably picky in this respect just because any unexpected sound really bugs the heck out of me while I'm driving. I've done several long road trips with drive units making the humming sound and it really drives me crazy. Some others might not notice it or not be as bothered with it, so not bother asking to get it fixed. I suspect this has something to do with it.
Again, this is exactly where I'm at. But try 20 visits in less than half that time. There is definitely a level of putting up with a problem. Squeaks, rattles, trim pieces are all things we should not have to deal with in the first place, but the SC takes care of them as they should and I'm satisfied with that (note: not necessarily happy about the problem, but satisfied it's been taken care of).
The major mechanical problems, like fans, chargers, and drive-units may or may not be related to how the car is driven. But a very important thing to realize is that a driver should not pay 100k+ for a car and then be able to easily "out-drive" it. I do not think you should be pulling the ABS fuse and doing smoky burn-outs, but if you decide to get on the freeway and utilize the ability to get up to 60mph in under 4 seconds, then there shouldn't be any issue with that; even if you do it everyday. They advertise the car as being capable to an extent, and if it is turning out it isn't, that is very frustrating. Hence the direction this thread has taken.
**Now rightly so, the car has the ability to limit it's performance, for example the "limp mode" people talk about. I'm ok with this since it means Tesla is trying to prevent excessive wear and tear. And it seems the implementation of this is very good. When I've needed the car to perform, it's never told me no. What I am suspecting is that they would have to excessively nerf the car to prevent DU problems on RWD vehicles to the point where it would not perform as advertised the majority of the time. As an owner, this is what I would have a problem with as would everyone else.
Again, as kennybobby stated, if the DU problems can be traced to a worn part, then I say they either re-design it (unlikely and more expensive) or make that a regular maintenance item. That way, a customer never has to deal with it failing and they rarely have to deal with the symptoms. Although, I will add that for ampedrealtor, the latter would not have necessarily saved him that first DU.
I raised this question in the infamous 691HP thread. I submit the AWD eliminates/mitigates the conditions of stress that would lead to a pre-mature DU failure (possibly pushing it out past the 8yr mark depending on driving style). It would do this by a 50/50 split in stress on 85D drivetrain, and XX% reduction to rear motor on P85D with the slack being picked up by the front motor. The two things that would prove this would be DU unit failure rates on AWD and 4-wheel dyno on P85D; neither of which we have BTW.