If two cars travelling the same direction contact each other such that the front axle of one car bumps the rear axle of the other (the car in front), it's usually the car in front that has the safety problem. This is the same principle behind the PIT maneuver.

If there's a rear end collision severe enough that the axles are contacting each other, both parties have a safety problem.

I wasn't talking about that. I meant lateral motion

I didn’t mention safety issues