@Cyan No clue if these features are possible or already exist, but here are my ideas:
Tricky Foot Bails
If the suspect vehicle receives extensive damage or the pursuit is prolonged, they could pick a specific location to foot bail. For example, if they happen to approach a metro station or a tight alleyway, the occupants could run toward that direction. If not on their toes, the player could easily lose the suspects.
Similarly, the vehicle could temporarily stop to allow their passenger to foot bail while the driver continues. It might also work vice versa, as the driver could exit their vehicle and surrender to police, but the passenger takes the wheel. This scenario would be hectic especially with more occupants.
Traffic Stop Reactions
Drivers could act disobedient once a traffic stop is initiated. To elaborate, they could slam their breaks and exit their vehicle, subsequently yelling obscenities. Also, they could approach the officer or simply walk away from their vehicle.
Likewise, a paranoid passenger could flee from the traffic stop or go on the offensive, so a pursuit would start. Meanwhile, their driver could surrender or flee. This would add even more uncertainty to 'routine' stops.
Conclusion
As I conclude, my idea is that these events would be fairly rare, so they're not ridiculously repetitive. If not a priority for the FR team, it would be interesting to see plugin developers pick these up, as they might be interested in these scenarios. I would love to see a similar implementation.
Lastly, being an avid LSPDFR player, thank you and the team for such an amazing modification!