Usually (or atleast Swedish military) use the AT-4 in groups in other words several soldiers with one each shooting at one target. Its better then having one guy with say RPG that has to reload in which the tank will have spotted this soldier and taken him out. And they are cheap!
And when your done you just throw them away which will result in alot less to carry around on, when one with an RPG will have to carry it around when hes done, and if the enemy gets hold of it and ammo they can reuse it, this can't be done with an AT-4
We also use the carl gustav that can be reloaded and reused