If your entire argument is based around stuff you've seen in movies, I don't think it's going to be terribly convincing.
There's no guarantee, a gangster could just follow you to wherever you moved, or could say "you don't have to pay" and come by the next day and break your legs. Or they could show up without notice and demand that you pay twice what everyone else does. Because extortion is illegal, so it doesn't follow any rules.
Here's some obvious differences:
The fact that extortion and taxes both share two properties (the potential use of force, and the exchange of money) doesn't mean that they're the same thing.