Every since I found out that the first digits of any credit card denote the issuer identifier (i.e., folks can tell who issued a credit card and what type it is just from the first digit or two) I’ve been annoyed almost each time I have to input credit card information on the web. Any decent credit card system knows that if a sixteen digit credit card number starts with 4, it’s a Visa. And yet, each time anyone buys anything on the web, they must select "Visa" from the drop-down box. On a certain level we all know this; People in stores and restaurants never have to select the type of card before swiping.
When I’m feeling generous, I imagine this is so that the credit card companies can give an extra reminder that they only accept certain credit cards — not being able to select a card type in an "essential" input field constrained to multiple choices is a pretty strong reminder.
When I’m feeling less generous, I suspect it might be so that the companies can subtly remind us that they have their own brand credit cards that we might like to acquire.