AARP is a non-profit corporation completely un-affiliated with the government.
Some financial references from
http://en.wikipedia.org/wiki/AARPAARP's total revenue for 2006 was approximately $1 billion and it spent $23 million on lobbying
AARP earns more income from selling insurance to members than it does from membership dues.
According to AARP's 2008 Consolidated financials, it was paid $652,000,000 in royalties from insurance companies that sold products referred by AARP. AARP also received an additional $120,000,000 for the ads placed in its publications.
If you read the whole article they aren’t without controversy but they also sound like they are a pretty well run organization. If you don’t like them don’t join or use any of their services. I haven’t previously joined but seeing as they’re willing to advertise (which is what sponsorship is) via racing, I think I will.