how would you model the very real possibility of anti tank friendly fire on captured units ? In MBT, you might say ubiquitous radio, but I don't think the devs would be happy with abusing the networked "features"
I would counter that you don't know the code to speak on the open channels, and certainly can't speak native on their encrypted channels when they appear.
in WW2, even worse, as you most likely have to rely on messenger or signals to communicate back with HQ.
Make it too easy and without consequence, and you break the game from a balance perspective, as without reworking the AI, it might never be able to see the captured vehicle as a proper enemy.
This would be a major change (unless I'm sorely mistaken)
Not worth the headaches and reworking of existing content, I think.