The first sentence simply means that "rehabilitation" is just a word made up by politicians. Why? Because without this concept these particular bureaucrats would have no job. You see, in the U.S. there are a number of government officials who some people say are just doing unnecessary jobs for which they get paid. Hard to believe, isn't it?
As for the second sentence, "that" would normally be required in written English, but this has over the years become a common phrase: "Not a day goes by (but that) I don't regret having left that girl." It arose as a colloquialism but has now been pretty much accepted both in speech and writing.
So what's the next movie?
Student or Learner