One of the problems is that patent applicants in the U.S. have no obligation to submit a competent prior-art search; it's the job of the patent examiner to do a prior-art search. Every time the USPTO issues a patent, in effect it's making national economic policy, yet someone seeking a patent need only disclose whatever prior art of which he or she (and/or the patent attorney) happens to be aware. That's like saying that a Ph.D student doesn't need to do a literature search for her dissertation because some junior faculty member will do the search — and then if that junior faculty member judges the dissertation to be acceptable (possibly in consultation with a senior faculty member), then the student gets her degree. The flaws in that arrangement should be obvious, and yet that's how U.S. patents are granted.