I'd suggest that on the car you are driving, it is defective! I've driven a good dozen cars with lane assist, and I have never, ever experienced anything like that.I managed to crash my car when we had snow a few weeks back and I've been given a Toyota Aygo as a courtesy car. It's so bad, I'm a relatively new driver and have only driven a few cars but I don't know why anyone would make a car this bad.
It has lane centering assist and in my opinion it's a crash waiting to happen on winding roads or anywhere you have to overtake parked cars. If you have to go around a parked car it pulls you back into it's path. I try to remember to turn it off each trip but it's caught me out a couple of times.
Not noticeable on dual carriageways or motorways as indicating disables it I believe, but I hate it.