The point is only to host them on your server (or mess with them by yourself offline I guess) and then enable downloading so people can grab them (most vehicles don't take long to grab) and play with you.
But of course you have to have the vehicles enabled on the map or else it's just useful on "cheats" servers.
I see your point.
I forget the exact directory bots.txt is in, maybe ext_data/ or something like that. Without my pc I can't look it up, but just sift through the assets pk3 files, take a few minutes and you will eventually find it, trust me.