Because the only people that have the power to remove the means to piggy-back are the ones that use it all the time. Usually stuff is tossed in that only helps a local district so that when the politician returns home, he can brag that he bought them a new bridge or something. Everyone seems to do it, so nobody wants to do anything about it.

Another attempt I saw to cut down on this was to attach the person's name to such last minute additions. While this has more to do with "pork" than stuff like gambling bans, I've heard it has severely helped cut down on pork added to bills. Of course, I heard it from someone being interviewed who helped write the legislation...

I forget the name of it, but a Google search found this:

Quote:
The reforms -- part of a much larger bill aimed at curtailing the influence of lobbyists on Congress -- would require greater disclosure about special projects inserted into spending bills by lawmakers, also known as earmarks or pork. Most significantly, the legislation would require members of Congress to attach their names to their proposed earmarks, which sometimes are inserted secretly and anonymously.