A lot of it is that EV1's pushed the Security on its merchant account up to a level that's almost impossible to replicate --- 100% address match. Unfortunately, there are discrepancies between the actual billing address of a card, the way it gets stored in the Authorize.net system (some seem to be verified with the post office and re-formatted while other's are left verbatim) and the length of the form fields from user input or when they're trasmitted to the merchant account.
A for instance I had issues with:
CODE
1234 Pleasant Hills Pk. Ste. 923
would be listed as "1234 Pleasant Hills Pk. Ste. 923" with the merchant, but when transmitted from their scripts, it would only send "1234 Pleasant Hills " (note the space) --- but then get the space would get filtered out. Then, of course, they reject it because the address didn't match.
It also gets really bad with Suite & Apartment numbers, since almost *none* of EV1's forms have an "address2" line --- and if your billing address is
CODE
123 Main Street
Suite 1234
then you can *never* put your address into the field and get it to match unless you completely omit the Suite.
I can understand any merchant trying to get rid of fraudulent charges, but as illustrated, there are simply too many variables that make Full Address Checking largely useless. The alternative, of course, is to use either Zip+4, Zip + Street #, or Zip + Partial Address (first x characters).