5,000 feet deep? Probably just above freezing.
The average person has NO IDEA how alien and out of this world a mile deep is. It is totally dark, pressures beyond belief and life almost non-existent except for a few things that only exist down there. It would almost be more difficult to put a manned community a mile down than on the moon.
Working on the surface has all the advantages without any drawbacks if only the politicians had brains.