My guess is partly because they are not as accurate, and maybe partly because testing facilities bought the ones that take more time in the beginning and aren’t laying out more money for another type of test kit.
The quick ones aren’t PCR testing so they are good for if someone is shedding a lot of virus, but the PCR will detect smaller amounts of virus.
The military always has things that the private sector doesn’t always have, or doesn’t have in quantity. The military will get vaccinated first. They don’t follow the same regulations or standards as the states for many things.
I grew up in military care and some of the tests and treatments I received none of my other peers had except for other military friends.
Your son was flying, so they wanted to know at that moment is he likely shedding enough virus to infect people.
Mostly, the answer is probably you can’t have the same because of money, but also because the average person won’t get tested day after day, so if they have a suspicion they are likely to be exposed or sick, the PCR will be most likely to detect it.