I think a reasonable approach would be FLIGHT pay, ON DUTY pay, and Per Diem.

Flight pay is for when flying, per diem is for off duty but still on a trip. ON DUTY pay would be for all those other times you mentioned. It seems unreasonable to be paid 100-300 dollars an hour to have an airport sit.....but it’s also unreasonable that we are paid a few dollars an hour for those same duties. There should be a rate we are paid during our duty day that consists of time other than block pay. $20-$30 an hour maybe? Who knows? It’s a novel concept that’s very unlikely to gain any traction.