Real quick after this becomes normal, somebody is making an extra few cents by buying 10 bunches of asparagus from a farmer, redividing them and selling 11 bunches to customers.

What gets done about that? Weights and Measures. I agree to pay you $3 for a spigglywig of asparagus.

Then I worry your spigglywig is deliberately under-size. The market town gets an officer to check you're selling asparagus in correct spigglywigs, and next thing you know you've got a multi-billion dollar metrology (the science of measuring things) research lab and they're defining the fundamental constants of nature so as to be right certain exactly how much a spigglywig is every time.

So yes, "free market" is at best a model that can only be approximated and at worst it's a filthy lie.