"I was simply wondering why the brownsers and the credit card companies do not filter these sites if they are illegal"

Money..... A credit card company will only go after illegal transactions if it saves them money, makes them look good, or they are forced to.

Look at how a credit card company makes money. They make money per transaction. It doesn't matter if the transaction is legal or not. Web servers are the same. They get paid if the merchanise is legal or not. Unless a website is stealing card numbers or hijacking a domain the companies make money.

So when a website sells illegal goods the only one who loses is the software manufacturer and the government. You get cheap software, the seller makes his profit, the credit card company gets its percentage, the webhost gets paid. Of course you may also get buggy software that is not what it is supposed to be, the credit card company and the webhost might get stiffed but what do you expect when you deal with thieves.

Really the people with the most incentive to close down these sites is the government... they loose tax revenue. But if a government doesn't tax these transactions why would they close them down?