> Technically, any justice administered by a mob is targetting innocents. At least, it used to be that things like fair trials were a requirement to establish guilt.

No, people have never, as a general rule, been protected from social consequences of actual or perceived wrongdoing until proven guilty in a trial, only (and this mostly recently, historically, and adhering to far-from-universal principals of restraint) from certain (generally not all) government-imposed consequences.