I assume the same way a car collides with a bicycle, stationary object, pedestrian. If someone claims against your car insurance they either settle, investigate, or reject liability. If the figure is small they just settle and hit you with higher premiums for the next 5 years.
The onus is on the car driver to drive with due care and responsibility. Other cars, pedestrians, bicycles, scooters, motorbikes can all behave in unexpected manners so the risks get higher the more of them on the road, I have seen scooter, electrical bikes and those small not quiet a bike or a motorbike all behaving terribly on the roads. But I also have seen many drivers increasingly behave badly.
My daughter has a small car and is a careful drive but she is being dinged over and over, 2 hits when the car was parked and once from a lane encroachment.
It is getting worse out there and inevitably premiums are going to go up.
Hopefully the new powers the guards have will at least see uninsured cars taken off the road, the estimate is that 1 in 12 drivers are un-insured.