Expect an error but this will depend on the brand.

"Smudging" is a common trick. Just dab some face oil on the lens, just enough so it can't get detail but not so much that the system can tell there's a covering.

Not sure about the systems on cars in the EU, but I got a loaner 2025 Hyundai Tuscon when my EV was in the shop. It had some driver attention monitoring feature with a camera above the steering wheel staring me in the eyes. I covered it with a piece of black electrical tape. It popped a little warning on the main display (IIRC, a crossed out eye, but maybe I'm confusing with Subaru Eyesight) when the car first started up, showing that the camera wasn't working, then proceeded to be silent for the rest of the drive.

I dunno if that'll fly going forward. I know I'll test it in every new car with this feature that I test drive though!

You can deactivate it, but has to be on every car start. It's so annoying having to tur off all that crap every single trip.

Sometimes i forget the lane assist ON and get nudged randomly at high speeds, so so scary.

Car starts quacking at you