What would a mil pilot have done in a 10+ year enlistment to have gotten only 500 hours ?
Surprisingly, the 'best trained' in military aviation tend to have the least amount of cockpit time - fighter pilots. You might only get 1-2 hours/day and that is not every day. Tanker and transport pilots are the gents (and ladies) that build time more quickly than their fighter counterparts. In 10 years time, I would imagine all categories would easily obtain the existing 750 hour mark, if aviation was pursued from the time service members signed up.
Generally, USN aviators typically come through their piloting career with a bare
minimum of 1000 hours, with 100 hours/year being the required minimum for currency. USAF, less so. The averages attained across all branches are mostly due to aircraft type flown and deployment status.