There are several ways to counter this and most servers allow vehicles to be put on bases.
1: get a little bird or other heli and halo jump onto base and blow the vehicle up.
2: get a MAAWS launcher and shoot the gun of the vehicle it will blow up.
3: get a Lynx\Ksvk\Barret and shoot the gun to disable it.
4: raid the base and hack the flag and team up with others that are tired of the base.
5: get a Blackfish and load a GMG vehicle or similar into it and paradrop it onto the base, both vehicles might blow up but hey accidents happen, and its allowed to ram with ground vehicles 😉
6: get a spitfire and learn to drop bombs accurate with it
There are probably more ways to do it, these are just the few i figured out in 5min