GPS is a US military system entirely payed for by taxpayers, that just spams out pings to any device listening. Civilian end users can’t transmit to it.

And it wasn’t freely available to civilians for years, until the Korean Airlines Flight 007 was shot down in 1993 by the Soviets due to a navigational error causing them to drift into Soviet airspace.

That's not funded by a private company, it's taxpayer funded.