Ya, bots are pretty rampant in bot games. The ones I have seen will usually just follow someone around from the start of the game, or walk up mid and keep dying to the tower.
It is possible to wins those though, just split push. Bots cannot defend against split push, so as long as you have 1 person that can clear the wave bot mid (where bots usually push down) you can 3 or even 2v5.