This is not new. This is how banking system works. It has been like that for years and years and years.

The ATM global network is a God Send to travelers who used were being gauged by the Buy/Sell differentials and no any viable alternatives to avoid such until the invention of ATM and the establishment of the global network - your individual transaction is being pooled with millions of others - big and small - among banks - to send back and forth in HUGE sum each and every day at the various settlement schedules, hence you enjoy the very favorable rate.

Besides, just think a little bit further, if what you conjure up is a good way to by pass the ATM fee or forex fee or what not, wouldn't you think why this is not a wide-spread practice, if it works? Many things just need a little common sense to think thru and a little google to verify.