I think the standard economists' reply is off-base in this case, because the problem is not a lack of information, but too much information. A typical credit card agreement fills up several 8.5 x 11 sheets of paper in very small print. The credit card company has many lawyers who collectively know every word in that document. Most people are incapable of understanding an entire credit-card agreement. People don't read them any more than they read the 10-page terms of agreement you have to click on to "agree to" with almost every piece of commercial (and even free) software you install nowadays. Did you know you are not allowed to use Cygwin at work? Did you know you cannot use Java to develop software for use in nuclear power applications? Did you even read to the end of this paragraph?

Would it be more acceptable to a libertarian to see the government legislate a limit on the length of different types of contracts that can be offered to consumers, than to legislate their content?

(While they're at it, I'd like to see a legal limit to the length of legislation, too. Like a law saying that Congress, in a given term, cannot pass more than 30 pages of legislation for every day they've been in session.)

Limiting length might have the result that contracts would get even harder to read, as lawyers used terser language to say things more succinctly. Wait - no, I'm not afraid of that happening.