That is the roleplay lol. There is gameplay limitations that kinda make it hard for cops to interact with players. Unless you want the realism of getting the new APD IDF cellphone message you like you're a Hamas soldier to pull over. I don't play APD and probably never will but you got to get in their shoes for a second.
Getting code 3'd is engagement and engagement allows you to shoot or flee. Most people shoot the APD. So APD is already on edge and probably hates giving chairtiability to most players. Cop interactivity in the state of the game is also very low. I like to split engagements into two categories. Engagements where you bring the fight to someone and engagements where they bring the fight to you. Cops will mostly always interact with players in the latter. Cops are most present during things like federal events and other events. So the reserve, blackwater, narco drops, gear drops, red radioactive, pharmaceuticals, apd gold escorts and evidence locker escorts. Every one of these events force the cops to come to you. You set the terms for the fight and this fight is 9 times out of 10 going to become a shootout. People don't do hostage taking and negotiations anymore so that roleplay avenue isn't really there that much anymore
So cops are stuck mostly fighting players who shoot them on site. When are times where cops can begin the engagement on their terms or as I say, when they bring the fight to you? Well its pretty short. You have generally 3 options. When you're robbing someone, when you're doing a run, and when you're driving to look for someone to vigi/rob. Note that most of the time, people won't give APD the chance to even roleplay after a code 3 since it's a shoot on site. So if you're robbing someone and APD pulls up, what is the incentive for APD to roleplay the situation? When you're doing a run or just driving around, what gives APD the incentive to pull you over and roleplay it out if they know that its 10x more likely you're going to shoot as soon as you're out your vehicle?
APD as a role kind of sucks to play if you're a small fry to. Higher-ups toss you into situations first to die in the meat grinder and they get the glory. The small power you get being the role of a cop is going to be abused since your higher-ups fuck you and most players try to fuck you so why not abuse the power you have and fuck doing roleplay with people who don't roleplay with you. APD has little reason to roleplay. And I say this as someone who has tons of super fun roleplay moments with APD.
Your soloution won't fix the role for APD, it'll kill the role because now you make it even harder for APD to get the chance to try and have fun roleplays with players outside of shoot-on-site events.
Welcome to the concept that power corrupts, you must be new on earth. Yeah high ranking cops are often dickheads. Here is your soloution though, read the APD handbook and learn your rights such as trial by combat. If cops break the APD handbook, report them. And if Support protects them, post on the forum of the cops clearly breaking rules and Support refusing to do anything. You won't find much sympathy for Support on here and most people hate the APD here too.
If you want to fix the issue of APD roleplaying, you need to fix a lot of other gameplay issues. While I have my own stance on how to do it, your soloution has a lot of flaws that ignore generally the limitations of roleplay interactions.