This I'm quite surprised about. I would've thought there would be a bigger push for HK to go UnionPay by allowing the same things that people with mainland-issued cards can do. Holding deposits are a given, and for card not present, BEA up here has asked me if I want to allow card-not-present/Alipay transactions on my debit card (on the other hand, they suddenly turned off out-of-mainland withdrawals and required me to come to a branch in person to re-enable that function, so I'm a bit annoyed with them), as have a couple of others (Standard Chartered has the least annoying online payment procedure so I usually use their debit card for Chinese online purchases). Or is the issue on the merchant side?