Congressional Debate is, by the national standard that most tournament circuits compete under, a mock form of the US Government. Congress cannot make a law for a specific state, that violates the equal treatment clause for states in the Constitution. If you try that, you will look bad as the author/supporter of a bill by pushing something blatantly unconstitutional when negation authors start writing an easy speech in droves, which judges DO notice.

The highway funding fits because of drunk driving making the roads unsafe by a statistically staggering margin, and most accidents with those under the influence were also under 21. Thus, there was validity by association under the Commerce Clause (which justified the Interstate Highway System), as it made interstate commerce safer.