Why Isn't Buchu Grown in the U.S.?

Can you provide any information about the plant or herb called buchu? Apparently, it's only grown outside the US (Cape Town, Africa) and has to be exported in? Any idea why? Is it possible to obtain the plant and grow in locally?

Buchu plants and seeds cannot imported into the U.S. due to USDA restrictions. All of the members of the Rutaceae family to which citrus belongs, cannot be imported into the U.S. We believe that the USDA has been excessive in banning all members of an entire plant family in order to protect the U.S. citrus industry. Because there are no lobbyists for gardeners and herb enthusiasts in Washington, and because government regulators tend to take the easy path and sweep everything up in their bans, far too many useful plants are unavailable in the U.S. as a result.
Buchu also is a challenge to grow. We have not been very successful in getting it to grow in our greenhouses, probably because of overwatering (it is a dryland plant). Here is a response to a previous question about growing buchu from seeds:
www.richters.com/questions-and-answers/04-19990908-3