Right, but banding together in mobs tends to precede the establishment of a state with laws, due process etc. Hence why we tend to be appalled by vigilantes (even the professionals do a pretty uneven job when it comes to enforcing our laws, letting everyone do it as a hobby is not likely to produce a better result?)

The _existing police_ is a banded together mob.

Citizen and all other private security firms operate under the same laws as any other individual or company. It’s not like these guys went out and started committing violent felonies...

The existing local police is a coalesced group effort. In some regions (like SF) the existing institutions are no longer effective. There is nothing surprising or particularly heinous about an attempt to create alternatives.