In the fights I've been in, anti-tank weaponry works fine. Why? Because you usually have about 5 or 6 guys all firing rockets from multiple directions at the tank at the same time, and if half of them hit then that tank is dead anyway.
One on one, no, I don't believe anti-tank weaponry should be a viable "solo" act against a tank unless the tank isn't paying attention. Which, again, DOES happen. Which, again, DOES REWARD the infantry soldier that takes the time and effort to find the right position (behind) the tank without getting facerolled in the process. But should you be able to stand in the middle of an open field and play chicken with a tank from 75m away, your rockets against his front armor and expect to win? Hell no.
As far as Phalanx turrets go, I generally have no problems with them either. It takes a good bit to bring one of them down, let alone just lining up the shots. As a defender in a Phalanx, I'm usually shredding tanks apart quite readily until the enemy gets to critical mass in terms of incoming armor. And that's the game - it's all about numbers most of the time. Incoming attackers put up a huge amount of armor and start pounding you with 150mm rounds from all directions, bombs up top and rockets to boot, of course one little stationary turret is going to die.
I don't really want to come off sounding like "You're playing it wrong", but it really does sound like there is a perception issue. I've been on both side of the fence too and you just have to take the good moments with the bad ones. For example, I have a huge love-hate relationship with ESF's. I love flying my reaver. I'd like to think I'm a decent pilot. Being in a tank on the ground, I can see a scythe or mossie come by and hit me with what feels like 2 rockets and I blow up. I take my reaver out, pound that magrider in the ass with probably 20 rockets and it's STILL going. Other days I'll go out and get kill after kill putting 4 rockets here, strafing with my gun there, taking out enemy liberators from 150m out with guns only, divebombing enemy ESF's with rockets and feeling like a god. And then there's that one infantry that just took an entire 12 rocket salvo, and he's still walking away. Or the one mossie I just hit with my guns, who turns around and somehow took me from 100% to 0% health in about 2 hits.
The game does stupid things sometimes, just set em aside, and whatever you do absolutely do NOT thing 1-on-1 balance. Ever. Especially never, ever thing "this versus that" balance. It'll make your brain hurt. Just remember - it's a war. A big war. It's not supposed to make sense. Squad up, go find a big fight, and shoot at the red triangles. It works way better that way.