The reason is pretty obvious. If they actually shipped prescription medications to people who do not have prescriptions, law enforcement could catch them by placing an order and, upon delivery (a crime), subpoena the bank that handled the credit card transaction for the identity of the seller. It's probably a lot easier and safer for the spammers to use the credit card information, which they solicit over an insecure connection--I tested it personally, without of course giving them a real credit card number--to buy things or get cash advances until the owner finds out and tells the bank.
It's quite possible that most victims do not go to law enforcement about this because they don't want to admit that they tried to order prescription medications illegally. It's standard practice for con men to involve their victims in a crime so the latter won't go to the police.
You can also report the advertised Web sites for fraudulent registration information to http://wdprs.internic.net/. There are two ways to do this; (1) send an E-mail to the purported registrant--don't use your personal or business account, because the spammer may retaliate against your address. If it bounces as undeliverable, that's a violation of ICANN's rules and cause for de-registration of the site. (2) Call the listed phone number (I use Skype for cheap international calls). If it's not a valid phone number, that is also cause for de-registration of the Web site. You can get the Web site's registration information from http://samspade.org/ by entering the domain name.
As an example, I got spams for several domains for which a phone number in China is listed as the contact. I called the number and was told by Skype that it was not a valid number. That is what I reported to ICANN.
Speaking of spammers, Barack Obama is one as shown by his campaign’s actions last year.
I get multiple messages from these people a day. And we have spam protectors here. I no longer open emails unless I know the person. I have to be careful not to wipe away legitimate orders.