@VitalsStable Utterly infuriating, and yep, even in 2021 this shit still fucking happens. Men say 'spending his money eh?' but I get women saying it too.
'Spending his money are ya?' a checkout operator will say? I always say (usually fairly cheerily,) 'we both earn money and it goes into our joint account, so I'm spending our money.' 
Sometimes they say 'oh right' and look baffled, (a husband pooling money with his wife is probably alien to them.) And other times, they go 'ooooh' 
like I am offended.
Not offended, just a bit baffled that in 2021, men AND women, think that a woman can't/doesn't earn her OWN money. Weird also, that it's women on checkouts - and in shops (ergo working women,) - who say it. THEY are working and earning money, so why assume I am spending my DH's money?
It's never young people either, always 45+.
Maybe it's some half-arsed attempt to make conversation. Like when my DH bumps into this one man he used to work with, he ALWAYS says 'what's this? Carrying twins?' whilst prodding his belly. Fat shaming him, even when he is only about 13 and a half stone, and 5 ft 10, and on some occasions, slimmer than them.
Some people just have useless social skills, but I do agree that the 'spending his money are ya?' line is super annoying!!!
And like another poster, DH has also had rude comments from random men AND random women, if they see him doing anything for me. Comments like 'got YOU well trained ain't she?' I do say 'he doesn't do anything he doesn't want to do, and neither do I. We do stuff for each other because we want to.'
Some people don't like it when you fire back, and often frown and look annoyed that you gave an answer to their cunty comment. Some don't know how to react and just look blank.. Basically, I am not going to stand there and take that shit.