Not allowed by whom? The New York Times documented, in its famous "Target knew someone was pregnant before the rest of the family did" article, that the non-numeric information is used:
"Whenever possible, Target assigns each shopper a unique code--known internally as the Guest ID number--that keeps tabs on everything they buy. 'If you use a credit card or a coupon, or fill out a survey, or mail in a refund, or call the customer help line, or open an e-mail we've sent you or visit our Web site, we'll record it and link it to your Guest ID,' [Target Stores statistician Andrew] Pole said. 'We want to know everything we can.'"
This isn't isolated to Target. Long time data aggregators like Acxiom collect electronic payment records on everyone. Incidentally, they perform contract work for the NSA which undoubtedly has unlimited access to Acxiom's entire dataset.
"Whenever possible, Target assigns each shopper a unique code--known internally as the Guest ID number--that keeps tabs on everything they buy. 'If you use a credit card or a coupon, or fill out a survey, or mail in a refund, or call the customer help line, or open an e-mail we've sent you or visit our Web site, we'll record it and link it to your Guest ID,' [Target Stores statistician Andrew] Pole said. 'We want to know everything we can.'"
http://www.nytimes.com/2012/02/19/magazine/shopping-habits.h...