The government is to some extent, much like a business. There is a cost to eveything you suggest. Given this is a majority rules society(in theory), how much say do enthusiasts really have? Even in an enthusiast hotspot like socal, I can look around me on any given road on an average day and find a very small percentage of vehicles have any performance mods.
While in an ideal world the legislators would certainly love to please law abiding citizens who simply have a passion for their cars much better, but the reality is that to try and localize such enforcements to a small group while trying to effectively realize the bigger goals is costly.
It sounds like you are suggesting that we allow certain motors from other countries. Which ones? And from which countries? Where do we draw the lines? Ultimately, the US can only effect a broad control over the cars sold here by the bigger manufacturers. Trying to enforce laws aimed at such a small part of commerce is hard enough already. There's just not enough consumer demand as a percentage of the population to justify the cost. Especially when there can be so many negative things that can lead to having to enforce and enact more laws. When it comes down to it it's all about money.
That said, I certainly encourage youto speak your mind about such topics but understand that we do have to pick and choose battles as well. Harrassment certainly has been an issue. It's become less of a problem for me, but I may not fit the "profile" anymore, so I don't know if it's as much a problem today or not. I do know that the exhaust noise laws were a wide open door for law enforcement to use to harass as most people in the profile had a modified exhaust. While I don't disagree with the intent of the exhaust noise laws, I certainly disliked the way officers abused them, even misinterpreting the laws in their favor. In case you were not around SEMA, and more specifically, the SEMA Action Network, helped to get the law changed to be more specific and offer a solution that is more fair to the public. I don't hear nearly as many stories of officers abusing the exhaust noise laws. If you perhaps want to hear more about what they do, consider getting their newsletter. I've been a subscriber since before the millenium.
Here's a link to their success page:
http://www.semasan.com/main/main.aspx?id=60085
And a link to current issues on teh table:
http://www.semasan.com/main/ma...ePage
They are much more effective than you may realize. They are however a nationwide organization and so CA is not their only focus.