Bell invented the transistor, not the government. The rest is history.
I am not aware of any subsidies that Microsoft, Apple, etc., received from the government, let alone massive subsidies. Intel received zero subsidies for the 8088 microprocessor, which really launched the computer industry. Not for the 286, 386, x86_64, etc., either.
> is directly attributable to decades of intervention by the US government
Oh come on. I've been in this business for 50 years, with zero government intervention (other than I pay my taxes).
DEC (maker of the famous PDP-10 and PDP-11) did not get subsidies from the government, although it sold equipment to the government.
> I'm not seeing the connection between a relative lack of regulation in the software industry and the price of FOSS software being (close to) zero
Regulations are a massive cost to industry. There are no regulations on software development. I don't have to get a permit to write software, or sell it. I do not need a license. I do not need any government approvals. I do not need any certifications. Anybody with a keyboard can write software and make it available under any terms they want (usually free!).
Has the government paid for any of this FOSS software? I've never received a dime from the government for my 26 year efforts in making FOSS software.
> or your larger assertion regarding free markets and prosperity in general.
The most prosperous economies in history and the world come from free markets, not socialist ones.