Panel gaps and other aspects of build quality don't matter in a world where Tesla competes on power train rather than fit and finish.

They matter much more when consumers choose between different EVs from competing marques.

If you can't get something as simple as panel gaps right, why would I trust you to get the brakes right?

By installing the brakes right. There's no correlation between those two things.

It would be like me saying to another automaker, how can I trust your brakes when the entertainment computer routinely crashes? Or how can I trust your suspension when your CVTs don't last as long as they should?

These things don't correlate that way.

The correlation is that both installation steps are happening in the same assembly line, in the same conditions, by the same workers/robots. Panel installation is a solved problem. Brake installation is a solved problem. Electronics installation is a solved problem.

Except one of those solved problems very clearly isn't "solved." This is something that stops assembly lines in other manufacturers. That it doesn't with Tesla signals that other assembly-line-stopping issues may also be ignored.