I've seen many bands that stopped in between songs for a minute to re-tune to a different tuning. As an audience member, I really didn't mind waiting a minute for the next song.
The auto-tuners take maybe half the time (at least, that's about how long the Robot took when I tried it at GC). So, taking a minute to tune vs. taking 30 seconds to tune... it doesn't seem like a function I would pay hundreds of dollars extra for.