Unfortunately, your credit card format may not be a problem with the webmasters, but the lawyers. I worked on credit card processing applications once upon a time. We were contractually obligated by our clearinghouse (First Data Corp) both to only submit credit card numbers in the exact format they were provided by the user, and also without spaces or dashes. So while it's a stupid limitation, it may not be the faults of web developers everywhere.

This was true a decade ago and may have changed, but that industry can be pretty slow to update.