disables lane assist presumably by people who changes without signals

No. By people who adapt their lane position to the situation, like cooperatively riding shoulder lines to not be mirror to mirror with a truck in the middle of a desert. By people driving vehicles that can't consistently pick a lane position. By people who have experienced the camera wrongly identifying a tight dashed line as a solid line and reacted aggressively. By people who have tried to fight lane assist politely, had the vehicle fail to allow it, exerted extra pressure on the wheel than should have been exerted at highway speeds, then had the system suddenly detect the input and relinquish control, jerking the whole car into the line or further. By people who've driven a system that picked a lane position based on the lines, came up to an exit lane cutout, had the vehicle glide into the new larger "center" and point off the road, then had the vehicle realize it lost the lines and relinquish control as you suddenly got pointed at the crash barrier, all in under a second (aka the Tesla method, disengage prior to crash, deny responsibility).

I have an older car (not a tesla, either) that has a system that stays disabled when I turn it off and isn't even a persistent lane assist, but more of an emergency drift correction system. I set it to vibrate the wheel without actually steering.

And I use my turn signals religiously.