alt Hacker NewsActually, they are. It's really more a question of with who and of course don't apply to classified material.
But the SHARE IT act really helps formalize what was already happening. Most code is shared and made public. It's paid for by the public. Though it's usually not easily searchable as it's distributed via different platforms, means, and may even require submitting a freedom of information request first. But in more cases than not, there is obligation to share when requested.
https://www.congress.gov/bill/118th-congress/house-bill/9566
The "when requested" is the point I was making. FOIA is how you request such software. If you want a copy of the elisp libraries I wrote to automate creation of field devices on military fuel farm SCADA systems, you'll have to submit an FOIA request. Unless someone at the DoD decides to share it out of the goodness of their hearts, you have to ask for it.