Could be they're invoking the Interstate Commerce clause found in Article I, Section 8 of the Constitution.  It was intended as an enumeration of Congressional authority over matters "among the several states", but the Supreme Court has in the past interpreted it as a source of national police power.

Since these lenders do business across state lines, it could be argued that the Commerce clause applies.  A stretch, maybe, but with today's courts, who knows?

Regards,
Scott Perry