You are right, a US PhD degree is in more demand in general. There is a reason our economic systems are not pure supply and demand though, because in that case

You are right, a US PhD degree is in more demand in general. There is a reason our economic systems are not pure supply and demand though, because in that case workers/environment eventually end up being exploited. The US would look very different without minimum wages, environmental protections, and a bunch of other regulations which limit supply and demand based exploitation.