Musk needs deregulation to keep autopilot on the market and Tesla on the road. He also knows and worked with Thiel who backs the new republican power base and probably has seen how much benefit that's brought Thiel. I imagine this also explains his interest in Twitter, a platform which would give him political influence.

Interestingly, back in the early days of the automobile people there were no "car accidents" rather "car murders" since the streets were mostly horses and pedestrians. Jay walking became a crime because of intensive lobbying by automobile manufacturers.

Deregulation has been a systematic effort by corporations to limit their liability for things that are not and should not be called accidents.