This argument is based on drastically different goals than the one that would support the fence being raised. While some individuals may want to take in illegal immigrants and provide them with generous welfare benefits and call that "comprehensive immigration reform", that is not what the majority of Americans want. They want illegal immigrants kept out of the country, and that in and of itself is a solution from their perspective, so to say that a fence distracts from the goal is just a straw-man. In the sense that it helps keep people out, it is working just as intended.  Erecting the fence and taking other measures (such as investigating employers who hire illegal immigrants) are by no means mutually exclusive, and we can do both to ensure that American jobs are going to people who are in America legally.