In my opinion, a realistic superhero setting would be regularly demonstrating that properly trained hero capes with combined-arms military and law enforcement support effectively have an "I win" button against self-styled supervillains. That's why it's critical to not allow a PRT/Protectorate split; sanctioned capes should be commissioned as federal agents and working in direct integration with law enforcement and/or military units.
Basically, at any time the "heroes" should be able to tell the villains, "I see your street gangbangers with AKs and raise you our friendly local National Guard company." If someone like Squealer wants to play Mad Max, they should be eating Hellfires from orbiting Reapers.
I understand the idea, but.... Look, there's dangerous gangs out there now. It's very, very rare, that even with the worst of them, the cops send in SWAT for much. They don't want an open war on the streets. Most of them are often known, but stopping them means giving up legal limits, and just sending out kill squads.
Nobody wants that.
There was a time in Worm where the National Guard were called in. It didn't help as much as it might. There's multiple reasons why, inc the lack of parahumans intergrated with the NG, but.... Part of it, I think, is it did work, but not for the more dangerous Capes. A minor guy, who can double his strength, he didn't mess with the guys with guns. The E88? The gang members, well, they didn't do anything on their own, but with Cape backing, sure. Half the Capes of the E88 could deal with the NG troops, up to and inc
tanks.
Most of the Capes of the Bay could deal with guns, unless somebody really good goes after them. Grue, making it impossible to see, Taylor, not even being on the same block, Bitch, giant monster dogs who could tank hits from Leviathan, Regent, who can make you shoot your friend..... That's just of the top of my head, and just from the Undersiders.
All of this, however, ignores the simple local cultural fact, that most local groups don't want to escalate that much. There's exceptions, sure. But, we're talking Brockton Bay, one of the worst cities in the US, and even there, most weren't killing random people. However, half the major Capes can kill hundreds in very short order. So, arrest them, if you can, sure. But, think twice about turning up with a bunch of heavly armed combat troops, because a bunch of the capes could easly kill everybody around. On the other hand, the same Capes might well end up dead themselves, so it turns into a uneasy balance, where damaged people keep themselves from going to far, and the PRT doesn't declare you somebody to kill on sight.
Kill Orders were a thing. That's when they go too far, that's when the best Gov killers come out.