Oskar Friedmann:
Oskar looked down at the vehicle machinegun.
"Found Two here. I can't see shit - there's no fucking LOS on anything hot. Staying here isn't going to do sweet fuck unless I get a driver to move me or an RPG team pops up to try and kill me. Requesting a driver or permission to dismount."
Firstly, the BTR machineguns (KPV and PKM) are located
above the gunners seat - the gunner sits inside the hull of the vehicle and uses a periscope.
Secondly, there is no gunners hatch - they use the side doors or rear passenger/cargo hatches just like the passengers.
Thirdly, Varis is still in the drivers seat, he's just poked his head and shoulders out to provide a better view and pop off a few rounds with his rifle.
Fourthly, you only need take a look at what's happened to the Humvee to see the value of armour, even light armour like the BTR or M113. Getting out is not a particularly good idea.
Currently, all the vehicles (although probably not the UAZ or Humvee so much) are providing valuable fire support - this doesn't mean they need to actually be firing, just ready to do so at a moments notice. It also doesn't have to actually inflict any casualties, just prevent the enemy firing accurately, or leaving cover. It's usually the infantry's role to close with the enemy and do the real damage.