Because the legislation doesn’t require that. And they want even less legislation. I mean, how does one even come up with a car made out of stainless steel with edges sharp like knives.
Rules made long before anyone would come up with electric-only doors outside a sci-fi fantasy. (OT how many "try to push open that deactivated door" does Star Trek have power episode, on average?)
[1] https://futurism.com/the-byte/four-die-trapped-burning-tesla