"Just amazing - harbored by friends in the Pakistani military for years while they received billions in aid from the US."

This is completely normal, and it's long been the case for the Taliban too. The Taliban operate, and sometimes govern, fearlessly and openly in parts of Pakistan. This includes proper towns and city districts, not just remote regions in the mountains. The old guard of Pakistan's Inter-Services Intelligence is largely pro-Taliban and provides political protection, funding, supplies, training, etc. Other parts of the Pakistani government help them too.