Unfortunately small fingers don't always offer enough resistance. You can test this yourself with your pinkie if you're game.
It's because there's actually quite a lot of resistance in closing the window even if unobstructed, and that amount of resistance varies through the closing process, and varies depending on how wet or dirty the seals and window are.
The car knows the current position of the window at all times, right? If it's also continuously monitoring the torque/resistance, something as smart as a Tesla should be able to figure this out.
Pinching is presumably only a risk in the last four inches of travel or so, yes? Until you actually contact the upper seal, the torque should be quite consistent for a given opening cycle - dry seals vs wet and old/dirty vs new will change the resistance a fair amount, but should be nearly the same throughout a given opening/closing - and could even be tracked/remembered over time if needed.
So with appropriate programming the car should be able to recognize when even a fairly small unexpected resistance increase occurs in the dangerous zone, and respond to it.
(I'm not suggesting that Tesla currently has more sensitive windows than other cars do - just that they have the knowledge and processing power to make it happen in a future firmware update.)