As you stated, its to clear the trim. The reason for this is to ensure a tight seal to eliminate wind noise. Without the overlap, the window system can allow flex and enable air leaks at the gasket which can be really annoying. The overlap alows for a tight window to gasket seal.

 

And repeated use of the manual release door handle (which doesn’t cause the window to drop) will tear the rubber trim.

 

It’s to clear the chrome trim and create a positive seal for the windows

 

Thanks everyone. It still seems like a complex solution to the problem, but I'm glad that I know understand why they did it.

 

Other manufacturer's cars do this window hop as well. It's not unique to Tesla.

 

I guess the follow-on question, why not just do framed windows? Less complex, right? Easier to seal?

 

Maybe to save a bit on weight, but my guess is mostly just aesthetics.

 

Frameless windows are more aerodynamic, because the frames cause drag.
I expect that when windows move up they also tighten against the trim and in the door. Preventing rattle and airleaks.

 

Frameless windows are more aerodynamic, because the frames cause drag.

Only if framed doors are design poorly. Same applies to poorly designed frameless windows.

Reason why Tesla does frameless style is due to simplicity. Framed windows, AFAIK, are noticeably more complex with not a lot of pros.

 

Obviously, inconsistent gaps are just that; inconsistent. Thus, gaps that shouldn't be big. AFAIK there may have been inconsistent gaps at the beginning of production for Tesla workers, but they are not there any more in the current production models.

Further: by definition a frame can be in the plane of the body panels, but the glass will never be - with frames.
However, frameless glass can be in the plane of the body panels. And it is.

Actually, doors with frameless windows are more complicated; controlling the position of the window.

EDIT: Yes, @OrangeJulius, 'window hop' is also done by other carmakers with frameless windows. Often those windows also move inward on that last inch.