Well the only reason military can own /pay for anything is because it takes our money in a first place. So unless there are specific security concerns civilians should be able to use whatever military tech they've paid for.
Military and government can pay for stuff also using deficit spending, which is not "our" money. It's either FED's money which they create (and thus steal value from us) or it's borrowed money from wealthy interests.
I wish you could download a lightweight map of the entire country. The way the selector rectangle works in my city makes it awkward to capture it well since its kinda longer east west rather than north south. If a garmin from 2002 could hold maps of the entire country, surely my iphone with 512gb of storage should be able to do it too.
That doesn't entitle them to access to military systems, either individually or as a collective. And surely citizens of other countries are not entitled to access to military systems.
The military serves the tax payer by preserving their sovereignty.
It's nice that they allow civilian use of GPS, but it doesn't follow that they need to. It's perfectly acceptable to say that a civilian organization, government or otherwise, is responsible for providing satellite-based location services for civilian use.
The way GPS is operated is very unusual. The military doesn't provide satphone service to people around the world; are you arguing that they should?