Here's how a double crossing bar owner got handled once back in the late 70's at a bar we played in East Texas.
3-night stand with rooms, loadout Sunday around noon. Bar owner told us he couldn't pay the full amount because there weren't enough people, drink sales, etc. Thing is, the place was packed all 3 nights. Much ensuing arguments, threats, etc.
Finally our lead singer said, "guys, let's just take what he's giving us and we'll never bother playing here again." which was completely out of character for the singer, who was kind of a hot-head. Then as we were about to pull out of the parking lot, he told me, "I forgot something, I'll be right back".
A few minutes later he comes hauling ass across the parking lot, jumped in the passenger side and yelled, "Go! Go!", tossing a paper bag across the seat full of cash rolls and a .38.
I should mention this was a Ford F100 with a camper shell pulling a repurposed horse trailer full of equipment, so there wasn't exactly a lot of "go" under the hood. Add to that, this wasn't the kind of bar owner to call 911.
About 6 months later, the owner was arrested, and later convicted for being part of an attempted hit on an undercover cop the last night we played there, which we heard about amongst the bar patrons, "didja hear what happened???" I suspect the only reason he and his friends didn't chase us down and kill us was to keep a low profile after the attempted hit went south.
I never touched a dollar of that cash, BTW, and HATED playing those places, which were probably like the redneck-meth versions of the old chitlin circuit, only rougher.
I wonder how a contract would've worked in those days.