A Proposal for Standardized, Processor-Enforced Contracts

Instead of arbitrarily regulating against this idea, I'd like to see the card processors, card networks or banks establish a standardized, open protocol for handling situations of this sort. There's no reason that a single card transaction always has to result in a single payment in a one-to-one relationship. In the Rewards Network example, a single card transaction results in two payments: one to the restaurant, and one to Rewards Network. Since the card processor verifies the transaction, neither side has to undertake expensive verification and collection tasks. It's a good deal for everyone involved.
(Taking the concept even further, a processor could handle many-to-many transactions, where a group of transactions fitting a certain criteria would trigger a split payment. Easy, once you have the initial mechanism in place.)
A neutral processor with a transaction-based funds allocation mechanism would enable all sorts of sales agency models that wouldn't work otherwise. For example, suppose that I wanted to create an affiliate program, where I offered 10 percent of sales revenue to people who refer new clients to me. First, you'd have to trust that I'll do the right thing and tip out. Sure, you can follow-up with your referrals to get an idea of what you should expect, but it's an imperfect verification system. In addition, you'd have to wait to get paid, at least until I got paid, plus at least a few days.
Instead, suppose we could sign a standard contract where I not only assigned to you the rights to 10 percent of revenues for clients that you bring in, but also gave you a guarantee that if one of your referrals came to me and paid with a certain credit card, that you'd get your 10 percent instantly. Furthermore, to create an incentive for your referral to use the preferred payment mechanism, let's also say that your customer gets cash-back or frequent-flier miles by paying with a certain card. Even if we've never met, you might take me up on the arrangement. As long as your referral used the designed payment mechanism, you'd get paid as soon as I do.
There would be a few issues to work out. You'd have to trust that I don't switch someone from the designated payment method to an off-the-books transaction by offering an incentive that's better than yours (i.e. the restaurant gives a cash discount). And I'd have to be confident that you're getting me customers that I couldn't get on my own, perhaps claiming a certain group of customers (i.e. the people who live within a half-mile of the restaurant) as exemptions to the agency agreement.
But overall, as Luke Froeb always says, mutually satisfactory transactions create wealth. Thus if bank-moderated agreements can structure and enforce contracts that wouldn't otherwise happen because of high contracting and verification costs, that's a clear benefit to the overall economy.
Now, all that's going to take is a few good systems. And some strategic marketing.