Because currently, we do not have anything approaching a free market. A free market would not have bailouts, bail-ins, subsidies, licensure requirements, exemptions from regulations as size increases, QE, ZIRP, rigged prices, etc.
Libertarians often say that a minimum wage goes “against liberty” because the freedom of the employer is infringed when the employer is required to pay workers a certain amount and that therefore, wages should be set by the free market (which we don’t have, as pointed out above). The only problem with this theory is that the “free market” usually tends toward free labor (NOTE: this sentence originally had quotation marks around the words “free labor”–see comments for explanation of why this was changed). Did they somehow miss the epidemic of involuntary servitude for lo these past several millenia?
Hell, there’s involuntary servitude for lo this millenium. Like, for right now. We live in prisons without bars. That is, we seem to be free. After all, we can choose Mexican over Chinese for dinner. We can drive a Jeep or maybe a Lexus. Maybe even both. We can fly to Easter Island or Machu Picchu–for a price. That price must be paid in dollars (or your own country’s fiat currency of choice). And the only (legal) way to get the dollars? Work. Toil. More often than not, for someone else. Someone else that you despise or that despises you.
One might understandably ask how working for a living is involuntary servitude. It’s called wage slavery. Not a new concept, certainly not original with me. Wikipedia has some great quotes in a really good article about wage slavery, but the one from Frederick Douglass stands out, as he knew from slavery:
“…experience demonstrates that there may be a slavery of wages only a little less galling and crushing in its effects than chattel slavery, and that this slavery of wages must go down with the other.”
So that’s what this minimum wage fight is all about: being a little better-paid wage slave. Hey, it’s a start…