Lane Departure Warning / blind spot warning

[h2onorth]

Hi All. The car I am speaking of is the anniversary model so I know its got limited safety features compared to the elite or ultimate.
My question is in this car the only warning you get in the car of lane departure is a flashing light (small) on the driver screen and sometimes a twitch on the steering wheel.
This is never going to stop a car departing from its lane so what's the point of it.
Secondly the warning in the wing mirror ,flash light , of undertaking or overtaking blind spot , again no sound warning; what's the point of it
I have driven Korean cars Kia/ Hyundai where the lane departure is rigorous and visually self steering except for sharp corners or narrow lanes.
Set up to the mark Vauxhall , way behind at present