[swartzentruber]

I'd have to say cultural -- historically, the US has been far less likely to ban or restrict many things than many other developed nations. Additionally, there's likely some judicial precedent involved. Our court system seems more likely than many other developed nations to overturn restrictive laws, unless there is a compelling (to them) public safety reason. For instance, there's quite a few restrictions around when and how sobriety checkpoints can be implemented.

Even though guns have come up earlier in the thread as something that is strictly licensed, the fact remains it is far easier to have a gun in the US than most or maybe all developed nations, for similar reasons.

Also, I think because we are a "big" country (land mass wise), and our public transit is typically far less developed than Europe for instance, many things related to driving are taken as a "right" in America, and face far fewer restrictions than other developed countries. So, to summarize, I'd say it's mostly how our judicial system approaches restrictive laws (like what you are proposing), informed by US culture and judicial precedent.