I think part of the problem is that the crew do not clearly communicate the consequences to the passengers (although there may be reasons for that). It should have been "Sir, if you do not return to your seat now, the plane will divert, you will be offloaded and arrested and charged $10k for the diversion, and will be banned from the airline". Then I am pretty sure there will be compliance, at least for most people who are not intoxicated or in a psychotic state.