In article , "Ray"
wrote:

Why do most military transports (C-130, C-17, C-5) have high wings,

Just some guesses:

It's easier to move equipment around on the tarmac when the
cargo aircraft have high wings.

The high wings on C-130 and C-17 allow for greater ground
clearance in the crappy places they fly in and out of.

Assuming the wingspar goes through the fuselage, it's
better to have the wingspar above the cargo floor than
below it.

--
Bob Noel