Which I why I say “sir,” “ma’am” or address ‘em by name.
Names are usually sufficient to separate ‘em out. Thai names don’t look anything like Japanese, Chinese or Korean. And there is enough difference between Japanese, Chinese and Korean names that there is a pretty good chance of getting it right - if you’ve seen them before.
I suppose ‘sir’ is better than ‘Hey you! Jap!’
;^P