I thought Teslas had radar for awhile though and they took it out?

They decided radar was superfluous at one point during the pandemic. By sheer coincidence by the time supply chains were getting fucked. Hitting delivery targets were more important than safety.

And they could have added radar and sonar to assist the cameras at least. The radar couldn’t give 3d data, but it could say “yo bro that’s a solid object, not the skyline” at least.

They did do that. It can be pretty difficult to make sense of conflicting data like that. Tesla may have decided to not bother to solve such issues and hope less sensor data makes it easier to interpret.

This is what Elon had to say about Tesla’s sophisticated radar data interpretation capabilities in 2016:

In fact, an additional level of sophistication – we are confident that we can use the radar to look beyond the car in front of you by bouncing the radar signal off the road and around the car. We are able to process that echo by using the unique signature of each radar pulse as well as the time of flight of the photon to determine  that what we are seeing is in fact an echo in front of the car that’s in front of you. So even if there’s something that was obscured directly both in vision and radar, we can use the bounce effect of the radar to look in front of that car and still brake.

It takes things to another level of safety.

I guess the ability to see around cars in front of you got lost in some software update along the line. Otherwise removing radar necessarily meant reducing the safety of the system, or Elon lied in 2016.

Was lidar that expensive in a car though? Because Infiniti started adding it in 2014 for the cruise control and those cars usually sell new for $50k if you get it fully loaded.

It depends on what you want to do with the sensors. Somewhat accurately mapping what’s immediately in front of the car to slightly improve speed matching and false positive/negative rates for emergency breaking comes at a cheaper price than the capability to fully map the surroundings fast and accurately enough for a computer to make correct decisions.