IMO: if you want to fight a cartel make a gang. Don't use the APD as a gang, that is not their purpose. Yes they are essentially the biggest gang on the server, but don't abuse it or be dicks. The APD's primary responsibility is to promote role play by using their PRIMARY WEAPON. I feel like at this point the cops are just saying its there primary weapon, but don't actually mean it.
I have found through my own interactions with cops that they use their voice less and less and use their sirens as primary weapons. I.E. Siren - Shoot - don't talk to me until we get to HQ (5 minute conversation with myself in a car traveling to HQ) - Have a one sided conversation with themselves and talk over me because they are adding charges and searching me with no real interest in having a conversation or responding to me but to go through the motions. I would understand if people are HVTs and hey there is a policy for that, but experiencing this type of interaction more and more makes me lose faith, which has been dwindling ever since I started playing cop. I do my best to RP at every corner, but when it comes to cops, those that actually converse with me are few and far between. They are more interested in going through the motions, and to hurry up so they can move on.
Cops go almost anywhere...yes there are restrictions, but that is the balance. If you want to go some where like rebel, black market, or a cartel...pursue people into those places. I agree with @LaGrange, cops dominate when they show up at a cartel or rebel and it is DEMORALIZING. I do not typically play with big gangs, and when I do play with a group its normally very small. So when my group and I are trying to gear up at rebel for a fight and the cops show up, the fun is one sided. Do the cops struggle when they gear up? No, why? because they spawn with their gear.
Is fighting a cartel fun for the cops? Sure its fun for the cops and you can justify it by saying "hey we lethaled them, they should thank us because they didn't go to jail". Cool, but isn't the point of the APD to promote role playing? Justify going to cartels and saying its fun for both sides is like a doctor saying hey we fixed your broken leg by chopping it off.