Can these CKM places really beat ATM/credit card rates by more than, say, 2%? I really don't understand the rationale for using them unless they can... Given that these days you should be able to get 1% at least back on credit card spending through miles etc then you only need cash for the things that need cash. Which is taxis and a few low end food joints (and Octopus cards for non-residents). I simply don't see the justification for using them for people who have credit cards and aren't in a situation where they have to spend in cash.

For high-stakes gambling I get it, but not otherwise. Please could someone explain (with examples)?