New cars are mandated to have rearview cameras as a safety feature, so that you see that child / object you’re about to run over as you’re backing up. Many cars have more than just one, to assist with parking or in a poorly designed vehicle (I’m looking at you, raised pick’em up twuck) to assist with visibility. Recording what you can see is a different matter, & while easy enough, adds complexity (flash memory that will be overwritten tens of thousands of times over the course of years in all conditions from cold of winter to summer heatwaves & needs to do that reliably) & cost to the price of the vehicle. Further, recording what you see is going more towards the liability side of things than the safety side of the equation.
Teslas do have some recording capability; however, better recording uses energy/battery percentage, & as I learned from another poster here, doesn’t even save all that much, only the last hour’s worth.
Damn you, @LSLGuy, inserting your helpful link after I started my reply! {shakes fist} In that article, both the Mercedes & Tesla look like they need a USB stick; what happens when you take it out to look at that moose/bird/[beenado](https://boards.straightdope.com/t/bee-nado-really/1007635/) & forget to put it back in your car when you go out again.