I think that I speak on behalf of most cop players when I say that we don't want more money, we don't want it to be easier to arrest criminals, we don't want a faster car or change of rules to make our gameplay easier. Will some people be happy if those things happened? Sure. Would cops become more active? No. Something that becomes clear after only a few days of playing as a cop is that your experience is very limited. Some people tend to say that cops can attend all the criminal activities and that both sides have access to same variety of choices.
This is absolutely untrue, let us take BR for example; yes it is true that both criminals and cops get to take part of BR, however criminals decide where and when, they choose their team before the start, they assign crackers, they organize defenses, they collect money and deliver it somewhere. What do cops do at BR in comparison? They show up and arrest people.
When there's a jailbreak, criminal has to operate the gates and organize defense as well as a way to get out. Cops on the other hand do the same what they did in BR, they show up and arrest people. A turf war is happening between two gangs, they're spraying grafitti and taking control of the area, they take multiple areas of the map and compete for map domination. Meanwhile, cops once again show up and arrest people. This pattern happens everywhere else, whatever the situation might be the cop player will always do the same thing, no matter where he goes.
For as long as cop gameplay is so limited and repetitive, people will get bored of it and go inactive. You won't get them active by giving them more money, weapons or cars, bringing new content to criminals then saying "cops can come to arrest at this new place too" doesn't make it new content for cops. Cops are treated as NPCs which are there only to respond to whatever criminals do. Until there are some serious changes made to cop gameplay rather than changes to cop/crim balance, people will find the experience boring because it really is boring.