By that logic, all laws are simply in place to perpetuate the status quo. While this may be true to some extent in differing examples, it creates a situation where one cannot trust the motivations of any establishment of order.
From a bottom-up perspective, this is probably the case (revenue seeking) for many police agencies who actively seek out ways to generate money where the ends justifies the means, where social safety is not the driving factor. I think this is a problem in itself that needs to be dealt with, but I think it is hard to argue against the fact that enforcing speed limits keeps a certain amount of people driving more carefully and therefore more safely. How these limits are established and enforced is important, but I think the dialogue is bordering on anti-speed-limit in general.