That’s an extremely simplistic view of commerce and human history. Robbery was very common before government. Robbery is still very common, but less so.
Fraud and dangerous products run rampant without government intervention. Basically, without a government to protect you, the likelihood that a mega corp will sell you something that will kill you is super high. Just look at how much regulation has improved auto safety in the last 70 years. And appliance safety, medical safety, travel safety, food safety, etc.
The kind of world that libertarians pine for is the kind of world that would kill them in a month.
I was responding to this:
In the prehistoric world, a person with something to sell or trade could mostly do so without interference, because everyone had similar physical power, making robbery more dangerous than it was worth.
And this:
Free markets mean people can enter the market and do whatever kind of business they please so long as someone else is willing to take that deal.