Well yeah I did start out with a partisan and flippant remark about the OP. Since I haven't been here all year I didn't want to jump into any long established discussions. Didn't the OP blame the Left exclusively for the gun free zone laws for this atrocity, which were in reality a bipartisan venture? Also, if we're going to blame the laws for failing to stop the behavior they were intended to restrict, do we blame all the murders committed on the laws against it? No of course not. Do you blame the rapist or the laws against rape for failing to stop the crime? Ridiculous!
See, again, you're conflating a discussion of "left and right" with "Democrat and Republican". A policy may be "bipartisan" in the sense of getting people from both political parties to vote for it (which is kinda the definition of "bipartisan"), but that doesn't apply to the philosophical divide of leftist and conservative. Gun-free zones are 100% leftist; there is no permutation in which they are remotely conservative. Therefore, the blame for any harm caused by them belongs to the left, not the right. The fact that Republican sometimes vote for leftist policies just demonstrates what I said before: left-think is more contagious than a flaming case of herpes.
Furthermore, we are not blaming laws for failing to stop behavior; we are blaming them for
actively exacerbating that behavior. Gun-free zones not only do NOT prevent spree shooters from bringing guns into them to kill people, they ENCOURAGE them to go to those places for their slaughterfests, because they know all their targets will be defenseless. THAT is our objection.
Laws against murder in general act as a deterrent for most of society, including some criminals (who, for example, commit burglaries when no one is home, rather than when the family is present), but their primary purpose isn't to prevent murders so much as it is to offer a framework for which to arrest and punish people who commit them. More importantly in this context, they do not
actively encourage people to do what they prohibit.
As for stopping rape, in a lot of cases, I blame the same gun laws I'm blaming for school shootings, because they prevent the victims from being able to defend themselves.