It is profitable.
If terrorists disappeared tomorrow. Let's say we use our surgical strike weapons to target every cell every member, and in one hour they are gone. What would happen? Billions of dollars disappear from the pockets of everyone in the chain. Military contractors, drone maintenance, promotions, bonuses, career advancements, no more completed missions, medals, no job to go to.
So the direct financial and career incentive for everyone in the chain is to always make sure there is a stream of new terrorists, new cells, new intelligence chatter about "the Great Satan". And that is indirectly accomplished by indiscriminately bombing civilians. Everyone who is involved in picking the target and knows it is a funeral, will know civilians will die. I can't help but think they also know it is job insurance as well. They would be stupid not to.
American public via media has been tested enough during releases of so many atrocities, torture tapes, lies, monitoring that by now, I think they've built an accurate model of how much outrage will be generated and how much will actually threaten future operations, funding, reelection and so on (so far not much).
The bottom line, I don't even know and 100% believe them when they say these are all "mistakes". The incentives and the motivation, especially in the long term, is for them not to really care if civilians get bombed.