I mean, assuming someone wants to fix this problem, there are 2 possible fixes.
#1 - Reduce the amount of arrests required to level up so vigis exclusively target large enough bounties.
You end up with a buttload of vigis running spar 16s with little to long-term effort.
#2 - Add a rule so vigis can't camp common bounty areas
You end up with becoming a vigi being next to useless. Getting arrests in Kavala isn't quite a pog strat.
So far all the suggestions are limiting vigis. Perhaps something could be done to encourage them staying out of Therisa.
Maybe a random event that happens quite often (Depending on player count) could be added. 1 or 2 NPCs spawn at a random location on the map and they begin running in any direction (A marker pops up once every 2 mins or something). If the NPCs are tased and restrained, they can be delivered off at any vigi outpost, giving 50k and an arrest. If they are killed, they drop a considerabel amount of cash (Maybe like 200k). Zone around the NPC is KOS.
For this to be viable NPCs would have to be taseable on the first place, but adding event like this is probably the solution.
I don't think them camping rebels is a problem, since even rebel retards often camp.