Sweden has provided another example, via The Croydonian:
"A municipality in eastern Sweden paid a biker gang 200,000 kronor to move away from the region."
The national government could have intervened and used state power to get rid of the biker gang but it wasn't necessary. The socially optimal (presuming that the municipalities leaders are properly representing their constituents) solution won out without outside legal intervention. The bikers didn't want to stay more than the locals wanted them gone. The locals made it worth their while to leave.