The market is not created by some third party. It simply represents the meeting point between what people are willing to buy for and what people are willing to sell for. That postdocs are willing to work for scraps relative to their skill level is indicative that supply has gone way beyond demand. For instance software developers also face similar issues of what you're mentioning with lower wage foreign workers willing to accept much less thus driving wages down, yet nonetheless high demand keeps wages high.

This is not particularly controversial and some have even suggested that starting to increasingly restrict the number of graduate students admitted could be the right path forward, as mentioned in this article [1] from John Hopkins: These and other suggestions for career preparation make one implicit assumption: that the nation needs the current number of biomedical scientists. A radically different approach to balancing the biomedical workforce equation would be to simply reduce the “supply” — that is, admit fewer students into science graduate programs. The article ends on what was apparently supposed to be an up beat note suggesting that instead of such draconian measures, perhaps we can look to people who are doing things like aiming to go teach high school science, with a doctorate.