Why aren't these companies required to pursue violations of any user agreements civilly?

The user agreement shows that it is presently in Version 1.0 beta.

But what if the original user agreement involved signing away rights to be notified of subsequent changes?

You will also be asked to accept a user agreement before submitting your request.

Look at the user agreement and any disclaimers on the site.

All we ask is that you don't violate our basic user agreement, like removing the ads.

An updated user agreement warning customers who sign in at the terminals about protecting their data has also been put into use.

Primarily, is there any logical reason why we are faced with their user agreement every time we update this?

If so, you must agree to such third party's user agreements, contracts and rules pertaining to the use of its service.

Just a single joke about reading the 'user agreement' run thin over an entire episode.