Why cavalry IDs?

[Shad]

This reminds me of a query that I posted a while back regarding trucks. After units are unloaded, and assuming the vehicle is not destroyed, why can't it be requisitioned by the opposing side for their transport purposes? While equine transports may run off, vehicles don't usually do so. So, if they aren't destroyed, why not ride to save a little energy?

My guesses:

Game Design Answer: to simplify the ruleset and flow of play

"Real World" Answer: I don't want to be driving an enemy vehicle through an active battlefield lest my own comrades shoot me!