@xp32 The U.S.A. is notorious for it's permissiveness towards companies to do whatever they want and for allowing shops to blacklist; I was surprised it was even legal in Japan to do so and I tried to search for it but couldn't find anyway.
Shops being able to blacklist on arbitrary grounds sounds like one of those strange things that is legal only in the U.S.A. where employers can also fire without notice or reason, something I know for a fact to not be legal in Japan.
I just looked up the local law regarding this in the Netherlands: shops may ban a customer for a maximum of 12 months only if said customer either violated the law within the shop, or violated clearly indicated house rules of the shop; arbitrary denial of service is not permitted.
I understand the marketing behind couple's discount, but why specifically make it a “couple” then rather than just for a “pair” or “group”?
Simply say that if more than one order together, all the others pay only 75% or something like that.