In every application I can think of off the top of my head, but mostly in the ones that apply to Tesla, you truly don't, except when the law or a contract says otherwise. I'm sure there are exceptions for things that don't apply to Tesla (or for that matter SpaceX).

Here's what's inside of every autonomous vehicle ever made: a message-passing subsystem, sensors, fusers, navigation, dynamic control, actuator device drivers, and thruster device drivers.

Sensors measure things and emit readings. Your most expensive, highest frequency general purpose sensors emit new readings at something too fast for a human but hella slow for a computer, like 100Hz-5KHz. Your common sensors, a video camera for instance, don't get even close to that. These sensors are often connected, even today because milspec companies hate modernity, via RS-232 serial cables. For those younger than 30, RS-232 is what non-Apple computers used for non-keyboard/mouse peripherals prior to the introduction of the first iMac in 1998 because USB didn't really take off until then.

Sensors send their readings via the message-passing subsystem to fusers.

Fusers take the readings from the sensors and, hur hur, "fuse" them together into a description of where the vehicle is and what the environment is like. This usually involves something like a kalman filter. Fusing even your very fastest sensors, the 5KHz IMUs of the world, is just a small bit of math and basically takes no time at all.

Fusers send their fused states via the message-passing subsystem to navigation.

Navigation takes the fused sense of self and the world and decides which direction to head and how fast to go. The objective could be something like hitting route waypoints or it could be something like staying in a lane and not being rear-ended and avoiding obstacles. Car navigation probably doesn't act on new input more frequently than 100Hz, you certainly can't act on new input more frequently than 100Hz, and it takes basically no time at all.

Navigation sends its directives via the message-passing subsystem to dynamic control.

Dynamic control takes navigation's "which way" and "how fast" directives and turns them into more realistic short-term goals accounting for hysteresis and other physical limitations of the system like minimum turn radius. This is just a small bit of math and basically takes no time at all.

Dynamic control sends its directives via the message-passing subsystem to the actuator and thruster drivers.

Actuator drivers convert dynamic control's "go more left" message into trying to go more left.

Thruster drivers convert dynamic control's "go more fast" message into trying to go more fast.

Actuator and thruster drivers send readings (hopefully) from the actuators and thrusters, because those are also sensors, back to dynamic control and fusion.

Sensors feed into fusers, fusers feed into nav, nav feeds into dynamic control, dynamic control feeds into actuation and thrust. When you have new data, you do something new with it which is technically doing the same old thing with it and just producing new output.

Now there aren't that many sensors. There are way fewer fusers. There's only one navigation. There's probably only one dynamic control, though there could be a couple.

Anything else that I haven't already described, like Waymo's machine learning object classifying 4D mustache adding hotdog detectors, are just sensors and fusers sitting on their own computers feeding new lat/lng/heading/speed to navigation at a rate that is hella slow for a computer. And for sure Waymo's convolutional neural network middle-out jaywalking yoga mom detector takes a lot of processing, but it's running on its own computer, not competing for resources, and emitting its fused readings at some hella slow for a computer rate.