Why doesn't the Afghan National Army have sufficient armored vehicles?

I know there a few old t-model tanks from the Soviet Union in the ANA's possession, but overall I think the total comes down to less than 100. I know the topography of Afghanistan makes tanks almost impractical for tactical support and that ANA personnel are not the most trustworthy. I did watch a few videos where ANA soldiers felt it was unfair that that they have to ride around in Ford Ranger pickups while US forces ride around in MRAPs. I am also aware that Afghanistan is landlocked and surrounded by hostile countries such as Pakistan and Iran; so importing a large fleet of tanks from old Soviet stocks (or any surplus) would be costly and ineffective, as well as the reality that if the ANA were to fall apart US-made equipment could fall into hostile possession. I am just wondering why the ANA couldn't be gradually issued some mothballed APCs or something, even if it would take some time for the ANA to train on them. I am no armchair general and do not even pretend to comprehend the complexities that are faced in Afghanistan at the moment, but I keep wondering about this issue in particular...