Given how many people treat speed limits as suggestions, at best, having your vehicle obey the limit would turn some people off of them.
I love to use trains to get around. I don’t need to do the work of driving, which puts every aspect of safety, navigation, and stress on me the whole trip. On the train I can sleep, do computer work, eat in a relaxed space, or talk with my kids without having to yell in each other’s ears to be heard.
Driving is a huge energy, stress, and time sink. It’s a plague upon our society. I’d rather have a train style space, but at least a self driving car would give a few of the benefits of the train. It’s a over technical inefficient and halfway there option compared to real transit, but it’s better than making me do it all myself.
I don’t usually speed much. It barely saves much time at the cost.of safety and mental stress. I’m also often tusing trains that usually go much faster than a car anyway, and sometimes up to 200+ mph. A self driving car (or any reasonable car) can’t even begin to touch real transit.