'With the advancement of car safety features, I'm wondering when dash cams that log speed just become part of the normal features of new cars and you can't turn them off. '
Probably wont be neccessary, as from 2022 all new cars are to be fitted with speed limiters and black boxes that will record details of speed, steering, braking etc. The police will have access to these when needed. You will be able to turn off the limiter if you wish, however the box will still record the details. When theres a collision they'll examin both vehicles boxes and apportion blame.