Only at a certain demand do you have a contract IME, and also for a certain level of event as well. Bar gigs aren't something I know to do contracts, even venues for bands that don't have a lot of pull. Reason usually is, if you have reason that shows your demand, then yes a contract sounds doable. If you don't have a fair bit of demand you can demonstrate, no club owner feels compelled to give you a safety net. This is PRIMARILY for original bands, cover bands should have a totally different setup as it's a totally different goal.
