Free will in the marketplace is a useful construct. But it's a construct nevertheless and can't explain everything.
About 15 years ago, I was interested in joining a gym. There was one near where I worked—it's part of a national chain that I'll call "23-Hour Fitness."* I went there on my 30-minute lunch break to check out their prices. What I got was an aggressive sales pitch that lasted about 45 minutes. They gave me a tour of the place and a sit down discussion over the various "membership options," which varied so slightly in price and services that it was hard tell the differences among them. When the people I was speaking with couldn't find a "membership rep" (who, apparently, was the only one there with authority to sign me up), I finally made my escape, telling them I had to get back to work.
This may seem weird to someone who hasn't experienced a similar ordeal or who has a stronger will than I do. But I felt guilty about leaving them without signing up, almost as if I had unfairly taken their time only to leave them in the lurch at the last minute. In fact, if they had found a "membership rep," odds are at least even that I would have signed up just to leave with a clear conscience. And for the record, I knew in the first 5 or 10 minutes that I didn't want to join at all.
What if I had signed and wanted out? There probably were (and are) some consumer protection policies that could have helped me. Maybe a grace period of 3 days. Maybe a cause of action in small claims court or other court. Maybe some government consumer protection commission. There probably also were (and are) some non-governmental opportunities. I could have gone to the "consumers' advocate" that most local media seem to have. I could have gone to the Better Business Bureau. I could have closed my checking account to prevent the automatic debits.
I'm not confident most of those things would have worked or that I would have availed myself of them. I can imagine feeling just as intimidated going in on day two of the grace period and speaking with these same folks as I had during the signup meeting. And I wouldn't even know how to pursue a claim in court. And the media option is luck of the draw (they probably get scores of complaints a month and can follow up only on a handful) while the BBB option amounts to a harmless tsk-tsk against the offending company. (Closing the checking account might have worked, but I'll leave that aside because it's not convenient to my narrative.)
My point, though, is that I might have done something because I felt compelled to even though I "knew" that I had no obligation to do it and "knew" doing it was a bad idea for me. That's a problem. But I'm not sure what solution—policy solution or otherwise—can adequately resolve that problem, where "adequately" means, I suppose, that which would protect others similarly situated. Grace periods can be lengthened. Causes of action can be made easier to pursue in court. Etc.
Some solutions are better than others. I wouldn't ban gym contracts, for example. And something is to be said for an adult taking responsibility for her or his actions. And at the end of the day I guess the important thing is I didn't sign, and the problem (for me, in that instance) is hypothetical.
*Disclosure: 23-Hour Fitness is not necessarily related to any organization with a similar sounding name.