Do credit cards have digits to represent the month of the year and nearly every web site requires that you select the month by its proper name?

Is it a fruad detection test to see if you are smart enough to do a conversion and thus worthy of a credit card?

Some people even think that putting the number and name on a pull down is a major coup:

Another score for 37signals:
when entering credit card information during the Basecamp subscription
purchase process, the dropdown menu for selecting an expiration date
contains both the numeral and name of each month. Similar
widgets in other checkout forms tend to list only numerals; I tend to
think with one or the other and rarely both, so it’s nice to see them
put together.

I actually see the named month much, much more than the numbers.  There has got to be a reason for this  It can’t be that hard to present a number like what is on the card.  I am curious.  Why do Internet merchants do this?