This isn't a failure of regulation. It's a failure of engineering culture. It's an industry fad or circle jerk, same as any other.

Blaming "but the law didn't say I couldn't do this" fails to properly ascribe blame and serves to excuse the peddlers of bad culture.

The Telsa handle and copycats are figment of stupid engineering circle jerk culture allowed to run unrestrained. These people are disposed to do all sorts of insane actuator and automation implementations to avoid having to design a simple part to withstand the force of a human operating it.

There are many ways to do a fold flush manual handle/lever and hook that up to a traditional door mechanism and/or make it automatic (the latter is a feature of every high end minivan side door in the past 20yr).

The problem isn't that there was no regulator saying no The problem is that they wanted to do the stupid at all. If there was a law forbidding this particular implementation of stupid they'd find a different one. You can't legislate them all. You have to solve the culture.

It can be both. That the engineers have bad culture means they suggest a moronic idea. That the regulators have been neutered means nobody stopped them.

That nobody stopped them means they got away with it, which means no motivation to change culture. And the circle jerk goes ‘round and round.