Less tickets = faster vehicles spawn.
So the less tickets you have the faster the spawn of vehicles. Can be used instead of giving the loosing team some extra asset. It's less gimmicky and less noticeable, which is good for the winning team - so they don't call "bullshit!" when being run over by a tank, but would be less effective at giving the losing team something to hold out for. Unless it's made very explicit, like a timer on the map or something.