Steven Horowitz posted The Story of the Schechter Brothers, which should be require reading for people like Michael Pollan:
As Shlaes points out, individual customers, both retailers and their customers, had the right to refuse individual animals. This minimized the risk of an unhealthy animal getting through when both seller and buyer did such inspections. And it ensured that the kosher laws served as a health code, or perhaps something more like the Underwriters Laboratory or Good Housekeeping seal.
As always, if a practice is unsustainable, unreasonable, or just not kosher in the food industry, one finds the government either mandating or incentivizing the practice. Why don't we know where our food comes from? You can thank F.D.R. and his minions. Michael Pollan ought to be a libertarian by now.