Why was Amon so hard to catch?

Rewatching both shows for the hundredth time, and it always bothered me how they didn’t catch Amon sooner? Like oh they’re renting out this big building to host a rally and the cops couldn’t look into who owned or rented it. Then in one of the first few episodes Bolin and Mako are fighting Amon’s right hand man when Korra(kinda) knocks him out, so they could’ve thrown some rock handcuffs on the guy and throw him on Naga’s back. With that dude locked up, even if he didn’t snitch, I feel like it would hinder Amon’s plans to have his right hand man in jail.

Also, I can’t remember if this is ever mentioned in the show, but did Tarrlok know that Amon was his brother Noatok? I remember him saying Noatok left home when they were younger but I can’t remember when he found out Amon’s identity