Emissions mandates and fuel mileage legislation. Everyone who has taken the fun out of driving. The reason why cars like the Dodge Challenger are $45k+ instead of the equivalent of $15k like they were in the late 60s and early 70s.
I understand the perceived slight there, considering this is a cycling forum, and I didn't intend to offend anyone. I ride because I like to, not because I believe Al Gore's story.