Oh, Widebody, there are plenty of medium and long range planes with a high wing. IL-76, AN-124, C-130, C-141, C-5, C-17, just to name a few of the most prominent examples.
It's a question about where it is most practical to have the wing main spar(s) pass through the fuselage. Just talk to those people (myself included!) who have banged their head against the lowered cieling in a F-50 or BAe-146 where the spar passes through.
On a passenger jet plane you simply make the best use of the fuselage space available when having the wing spar just under the cabin floor. And make room for baggage in front of and behind the spar.
On a roomy freighter you have only one room for payload, so the floor is put much lower leaving no room for the spar under the floor. And a flat floor is a must. It has one big disadvantage, the landing gear cannot be connected to the wing and its track becomes very narrow.
So I don't think that you will ever see a high wing ordinary passenger airliner.
Best regards, Preben Norholm
Always keep your number of landings equal to your number of take-offs