It's illegal to drive in slippers in certain countries, afaik. Slippers can.. um.. slip? Or whatever, they don't offer the same amount of control, that's for sure. Irrelevant 99.9% of the time, but for that 0.01%..

someone that cares about the safety of the car occupants and especially pedestrians. Many accidents are caused by improper footwear interfering with the pedals.

One thing is a tourist driving 10 minutes with slippers to go to the beach, another is a gig worker doing a 10 hours shift