system
Given the following post, respond as if you're commenting on Reddit:
human
[Deadpool movie] How does Sister Margaret's work as a business?

I haven't read the comics, if there's an explanation there feel free to bring it in.

From the movie, it's a dodgy bar in Canada.  Mercenaries hang out there, and people looking to hire mercenaries go there and put money in some sort of escrow account until the job is done?

We also see Weasel tell two newcomers that they're not allowed behind the bar, and have everyone draw guns when he says that.  We don't see why the patrons respect that rule.  He thanks them by saying, "thanks fellas for having my back."  We don't see any actual bouncers, other than the clientele.

So, how does Sister Margaret's maintain its place?  They have a wildly-illegal assassination-for-hire thing happening, a room full of (we can assume) volatile, violent people, lots of money passing through the place, and no obvious security to speak of.  How does it not get robbed or shaken down by the cops for protection?
gpt
Because it's where the jobs are posted and the clientele like it. If someone started busting up the place and scared off/killed the owner, then they would all have to find a new hub to hang out in and pick up jobs.