The advantadge to a company having in place an escrow payment against a student is that provided they provide the service the student has paid in front for to the escrow scheme then they WILL get paid - no chance of an issue with credit limits on a card. Due to this a BANK will release funding to a company, providing its credit worthy.
It replaces the tried and failed way of using students as the companies bank. Much safer than a company wondering if the funds are availible against xyz credit card. It is a two way method of protection