How do you "flip unto the curb by accident" if you are driving within the limits of the car and driver? Cars don't randomly spin out of control - when they do spin, it's almost always because the driver wasn't paying attention or was driving too fast for conditions.

Yes, sometimes, some other vehicle will swerve and force you off the road. That seems to be the exception, not the common case.

Very rarely, a mechanical fault will cause an accident. But, even those are generally do to lack of maintenance. Personal example - I was almost hit by a detached car wheel/tire a few months ago while riding my bicycle on a bike trail. The car was an old beater. No muffler, rusty, etc.