They wouldn't monitor everything. The computer systems would. They'd program some things in the computer systems that send out flags over certain behaviors. Or they can just use what they have on you inconvenience people who they feel the need to harass. Step out of line, bam, they've got a database on you ready to go.
It would be 90% automated.
Yes it's very much doable. The amount of manpower needed for this is smaller than you think.
You think this isn't feasible, yet we are only a few years out from discovering the absolutely massive phone monitoring this country was taking part in. This would be easier than that.
there comes a time where you have to either tell control freaks to fuck off or be prepared to be murdered along with your entire family as they purge every one in a paranoid death spiral.