Heh, were you at the Glen Allen SC around 2PM yesterday?
Anyway, I use auto-lock and it works well for me. I never have a problem with not shutting the door all the way, because it's obvious when you don't. When you close the door properly, there's a very distinctive sound as the window moves up into its slot in the roof. When that sound doesn't happen, the door isn't properly closed. I often fail to use enough force, and I always notice. But that's me, and others may vary.
I have had auto-lock fail a couple of times because I manually unlocked the car, which requires manually re-locking the car. So far I've always remembered within a couple of minutes and locked the car from my phone.
As long as the doors actually close, I'm not too worried about failing to lock the car. The handles still retract after a while, so it looks locked. John Q. Thief doesn't know you can still open the doors in that state. Obviously, we won't be able to rely on this forever if Tesla continues its massive rise in sales.