This. But I think it’s better to use marine autopilot system as a comparison - aircraft autopilots are closely monitored by three people (two in the cockpit, one on the ground as air traffic control). Not really comparable to a car.

Autopilot in a boat traditionally just turns the steering wheel for you. And all it does is maintain a desired direction of travel. Not even a destination, just a direction. So if wind or currents blow you off course, it’s not going to account for that. It also doesn’t control speed.

There are more advanced systems, but that’s traditionally how autopilot works.

Having said that, Tesla hasn’t just used the word “autopilot”. They also repeatedly refer to their system as “Full Self Driving”. And it kinda does that, as long as there isn’t a fire truck in the way.