Because far too many people don't return their shopping carts or flash headlights to warn fellow drivers of speed traps.
I feel like you can tell a lot about how compassionate a society is by the percentage of drivers that will warn others of speed traps.
Like... If you can't even do that bare minimum of flashing your lights when you pass a cop, what effort will you put forth to feed the homeless?
I do believe violence is sometimes justified, as do most anarchists. I obviously don't think there should be a law requiring someone to flash their lights or return shopping carts or whatever.
Any argument about what rights are exactly and how that relates to the state isn't one in going to go too deep into at 3:30am before I've had coffee. Haha. Suffice to say, though... In my conception of a just reading of rights and their application, a government that confines itself almost exclusively to an enforcement of negative rights is desirable from a practical standpoint. I believe for pragmatic reasons that it's preferable for some government to exist rather than assigning morality to the state. I believe the effect of applying a morality that denies government the right of force entirely is immorality in application. I understand that government will never confine itself to the low levels of a negative rights enforcement night watchmen state with a defensive military that I'd prefer, but also that any period of anarchy in the modern world would last for an even shorter amount of time than relative limited government.
Government is inevitable, especially if it's defined by a claimed monopoly on the use of force, and warlords accepted by enough victims are the versions of government that spring from any power vacuum. Is government, the very existence of it, moral? To me, that's the wrong question. It's existence is better than the alternative, in no small part because there really isn't one... At least not one that's sustainable or even really achievable in the modern world.
I know plenty of anarchists who believe, like Thereau, that humans will have anarchy when they're ready for it. That once we progressive far enough to handle it, that we will arrive.
Now... Maybe with the introduction of enough technology to change what we define as human as we integrate man and machine and allow some kind of symbiosis with our minds and AI or something, that could be a thing in the future I just can't easily conceive. But as far as naturally? I don't think mankind is even going in the right direction on a whole host of things that are necessary preconditions for any anarchy that's sustainable, functional, and desirable.