I'm pretty sure most politically active people aren't under constant surveillance.
Activists are people whose political action takes place outside our democratic structures.
If there are people out there who want to subvert the democratic process, denying those that disagree with them their rights to make their own judgement, and if there are people who want to cause disruption and damage to the lives and property of others, then keeping an eye on them sounds like good preventative policing.
There are always nutters in every generation who think they have a monopoly on virtue. Sometimes they can be dangerous.
