The cover tells all.
The Punisher is the most bastardly of all theother heroes. Unlike many other heroes, remember that Frank Castle started out as a villain, a bad guy directly trying to kill Spider-man. Eventually, he was re-branded into a hero and the rest is history.
But there is a keyword here: villain. Sure, the Punisher has become a hero and has gotten more heroic with each year, but, he hasn’t lost his roots completely. Bad guys get killed swiftly and with brutality. And the Punisher has a point, in that, he isn’t out to save the innocent, that wasn’t part of his motivation. He’s fighting a war against crime, villains, murders and thieves of the worst kind, and, in a war there are casualties: both innocent and not. Frank Castle just straight-up hates bad guys, it isn’t as complicated as we’d like it to be. There is no large moral code that the Punisher has created and lives by, he’s just a disciplined soldier,working to stay on the top of his game.
The Punisher doesn’t really care about the common people. Once again, they are just an unintentionally byproduct of killing criminals. The people don’t matter to him, everyone who he actually cared about is dead, buried, gone….there isn’t anything for him to really live for anymore besides killing each and every criminal he can. Eventually we see him grow and take a more active role in saving innocents but not to an extreme degree, yet he never waivers on his original creed: to kill the bad guys.
Not just killing them either: Punishing them. Torturing them if he feels like it. Killing them slowly. Of course at times just blasting them away into little pieces immediately after seeing them, other times beating them to death with his deft hands. Maybe he’s not a sadist but casing pain is the only thing he knows anymore.
Frank Castle is a hard bastard who literally doesn’t feel pain, doesn’t care about people really, and constantly fights in a war.