Complaining about lack of discipline in schools is like complaining about crooked politicians... if you don't vote them out, whose fault is it when they continue to be crooked?
The fact is that schools will only do what parents will tolerate; no more and no less. The example in this case occurs about twice a month in my class. Some little vulgarian utters an epithet in my class. I write a referral (the documentary portion of the disciplinary process). As part of this process, I call home to inform the parents of the referral. Later, the assistant principal will also call to inform the parents about the punishment decided. Both phone calls inevitably result in long, angry discussions with parents who complain that either the child should not be punished so "harshly" (usually an after-school detention or the like) for something so minor, or that they do not understand why the behavior is being punished at all.
Compare this with the manner in which principals and school boards fall all over themselves for every irate parent, and you will see the full measure of the problem. Every parent is all for strong discipline... so long as it is not their child.
The only parents who care enough to aggressively lobby principals and school boards about disciplinary problems are those parents whose kids are in trouble. Sure, every few years some parents will get involved and start really pushing the school board to address whatever the flavor-of-the-month issue is, but the movement inevitably falters as soon as one of the parents who is active in the movement has their little darling run afoul of the rule they have just worked so hard to create. Then it is back to the same old routine until the next brief uprising...
Sorry, but every single problem in public schools is caused, in part, by parents who don't care enough to get the problem changed. As someone who sees daily the great lengths that school administrations will go to mollify angry parents, there is no question that a concerted effort on the part of parents would change any problem they focused their energies on. But this is the great pitfall of government entities: because the institution is "free" and run by the government, the people who use the service feel no pressure to monitor it or take responsibility to see that it works correctly.
Kids will do whatever they can get away with (children need boundaries, and they push until they find them). When a school sets rules that it believes that the community wants, we expect the teachers and administrators to enforce those rules. But when parents are either indifferent or openly hostile to the enforcement of those rules, teachers and school administrators quickly learn that it is more trouble than it is worth to continue to strictly monitor those rules. And parents express their approval of this strategy through their silence. Schools reflect the community in which they operate, and their are serious problems in many American communities. Don't expect schools to change until the communities do... they are simply serving their populations...