"I understand the argument that wechat and alipay don't care about foreigners when it is a very small percentage of the market, but they still have a chance to pickup quite a lot of incremental revenue for very little cost if they can execute it."

It's the central government which has dictated the use of domestic bank accounts for name verification (with a possible exception, I'm not sure, for Hong Kong people). Point is, Alipay and Wechat aren't free to set up an alternative passport channel without government OK.