I can only guess it's a mix of local regulations and the fact that the RMB (CNY) isn't freely convertible. There's an HK version of WeChat pay which is more op

I can only guess it's a mix of local regulations and the fact that the RMB (CNY) isn't freely convertible. There's an HK version of WeChat pay which is more open but isn't very widely used since we have had the Octopus stored value card for nearly 25 years which serves a similar purpose. For everything else there's MasterCard (or Visa / AE).