Peculiar. I kind of assumed that the hills provided natural cover - and since the hilltops are so close to the base, you could easily run over to help if enemies from middle areas took potshots at those areas. Besides, I thought it would be a given that patrols get relieved by heavy support elements like Hunters and APCs if they ever begun to get bogged-down by rebels. Suppose my speculations were not completely realistic.
I think both sides think they're at a disadvantage since they are hyper-aware of their own factions shortcomings
Rebels have an extreme advantage in the sense that they can learn the entire map easily, since they arent limited to patrols and higher-ups. If cops aren't familiar with it beforehand and play CP exclusively it's likely they don't know where anythings located aside from like the city and the path towards it
They also have the manpower aspect down since they heavily outnumber CPs
On the contrary rebels are hyper-unorganized, most people act on their own accord and outside some groups they don't really have mass communications. Whatever they carry varies wildly from person to person, someone could have armour and a rifle while anothers armed with a pistol and four bullets
This is a double-edged sword since they have a shit ton of agency when it comes to handling situations without having to rely on anyone above them, but they can't work together for shit or come to a consensus 99% of the time
The cops in essence are fighting a guerilla force, which has no leader and can be anywhere at any time
On the contrary the rebels are faced with an unstoppable, hyper-armed military force
The cops have access to APCs, and now synths like Hunters which ripped apart the rebels earlier today. They also have gunships and choppers which lets them control the skies as long as rebels don't have RPGs
They're also way more organized and have people to lead them, and they usually don't wander without some goal in mind, they're also more likely to be using voice-comms. Their base is pretty much impenetrable as of now too. They also, at least to my knowledge have an infinite armoury at their disposal, although I might be wrong about that. Rebels have to be a bit more careful when it comes to wasting any material from food and water to ammo and armour.
The cops' problem is that they're clunky and slow, and just like rebels their experience with combat varies wildly, but they can't act as a guerilla force which means they have a single style of play avaliable (that is following their superiors orders). When they leave they stick to a clunky, huge APC and rely heavily on other stuff at their disposal. They're extremely powerful but they can be spotted from everywhere.
Just like rebels their tools are their double edged sword. They're slow and stick out like a sore thumb, and have to rely on their tools, but those tools like APCs and synths are extremely powerful and terrifying to rebels. The riskiest option they can take is going out alone without any support. If they play into that overwhelming firepower they can come out on top.