>> A lot of military software is built with tax money.
> And can that be opensource as well. What's your point?
Probably because military software likely contains military secrets that would be useful to an adversary.
A lot of espionage is focused on getting seemingly boring information like the performance characteristics of a radar system. If the radar system is run by software, and the software is made publicly available to anyone, an adversary country could learn what they want from the software (and do other things, like improve their jammers).
The government should definitely get the rights to the source code (and other IP) for military projects they fund, but I think it should still be kept secret (so not "open sourced" under a typical understanding of the term).
