why is that so?

Because at a guess your credit card screen says something like:

"Enter the details exactly as they appear on your card"

And on the card, they appear in capitals.

Additionally a LOT of data entry shops still require all of the data to be entered in all caps. The idea is that all caps are easier to read. I and l are harder to confuse if everything is in capitalized to read I and L instead. Thankfully most of us have format controls to switch text "To Capitalize" the first letter of each word which makes the conversion a no brainer ;)

Nice answer Deb...beat me to it....lol

Alternatively some people just type like that. Over the years we've had a few customers who e-mail us all in caps. They're all good people, but when you're used to caps meaning SHOUTING then it can set you on edge a bit :D

how true is the saying that most fraud enter the stolen credit card billing informaiton in CAPS (simply copy and paste)?

most of my fraud orders have been made in all small caps

edit: er I mean small letters