It goes a bit deeper than that: When you access a web site, you're subject to the terms and conditions of that web site. Here on the DIS, that means, for example, that you won't post irrelevancies in the wrong thread and won't engage in personal attacks. On most online store web sites, it means that reserve the right to cancel your order if the pricing is wrong. (I actually thought that Sears broke their terms and conditions, but a nice person in that Budget thread pointed out the part I missed -- Sears did right.)
We always have the option, as netizens, to simply not visit a web site if we don't like the terms and conditions.