If paying a pilot is the best way to get aid to those in need (cheaper and faster) then it is better that the charity pays him rather than using volunteer drivers in trucks.
The same goes for a administrator or a HR Manager or anyone else working in a charity. The best and most cost effective thing to do can often be to pay for a competent person.
the same applies in other walks of life; it's cheaper to pay a qualified person where I work than to employ an apprentice, even if they were not getting paid anything, as the apprentice is unskilled.
The end goal is to deliver goods or services to those who need them. Whatever does that in the most efficient manner is the best option. The bigger the organisation the more important it is that it is run by a core of full time skilled and competent people. That usually means they get paid.