I understand the point. I don't now how the mechanic works exactly, but isn't Infantry diving out of a vehicle path anyway?
I am not sure I quite understand the question, but if it is how instant snares work it is when the shooter is actually crushed. Since there is no animation the game triggers the response, i.e., damage and possible critical.
If you are asking about rounding infantry up, indeed infantry attempt to dodge an incoming tank, which is predictable to a degree, and a player can force them into a narrow area and then simply touch them with the tank to kill them.
If we make infantry ignore vehicles that could actually make things worse by causing infantry to make very obvious targets and requiring more micro on the infantry player's part. The beauty of the individual decision making at the computer end is that it removes the need for micro on the player's part and also allows likely better options to be taken because the player cannot control individuals, only squad choices.
If I still missed it ask me again and I will try to answer.
Side note, tanks must be moving on some axis for them to gain crush. Stationary tanks can be touched by infantry without threat.