Answer:
A couple, which have been discussed over the years, can be found in the threads. Two key ones are the necessity to track the income in the event it becomes tax reportable under a 1099 MISC, and a biggie, the need for some special privacy waivers, because when the bank pays the referring person, they have divulged that that the other party has an account with them. Privacy doesn't allow such disclosures.
I assume you'd only pay for referrals that result in accounts. If you paid for loans, RESPA applicable loans would have to be excluded.
First published on BankersOnline.com 1/3/05