I don’t know. My buddy was a maintenance tech in the Air Force and he has told me some of the shady shit that goes on. And I have seen him wrench and it ain’t pretty.
Military is different than fleet, and i know several mechanics that work fleet and they're some of the best around. Some at utility companies, some for government (local and state), some for construction companies, and some as equipment manufacturer mobile mechanics, almost all good paying union jobs with the accompanying training and tools. They even have guys in the operators that have their own service trucks and tools, they hire out and are paid just like welding rigs are. Ive ran jobs where we had enough welding machines going that the operators had the responsibility of starting them and keeping them running, and as the foreman running the job i had to supply the tools, fuel, parts, etc. so the operators could maintain them, hell i even had them doing the maintenence on my company truck during times when we didn't need him in a hoe
I had several operators over the course of the job, but my main one was excellent at both wrenching and operating, and later got me started in tree work for hire. He worked out a deal with a gas station that we would buy fuel exclusively from them (over 100 gallons of gas a week and a bunch more diesel too) but in return we would get free coffee, so the whole crew had free coffee every am, damn that was a good job.
It makes financial sense to maintain vehicles and equipment at the best possible condition, so they spend the money needed to do that because they need that stuff. Some of the really huge construction companies just buy all new stuff for the job, hire rig mechanics from the hall for maintenence, then turn around and sell everything at auction when the jobs done, the loss mitigated from not needing to store, maintain, and ship the stuff. That's the extreme, most hold onto stuff for a predetermined time then sell it off at auction, no matter the condition it goes, never used stuff included. I knew a few army mechanics but they all served in their 20s, i know there's older ones too but i would think the military has a much younger and less trained workforce than the fleet guys i know, most who have decades of experience of doing it for a living.