I think this is mostly a US thing. Why use yearly salary? You're not paid once a year, are you? Most likely once a month. Referencing monthly salary makes much more sense.
"I'm making 50k". Great, now I have to guess - dollars? Monthly? Yearly? If yearly then what's the monthly paycheck? Net? Gross?
But most pays are fortnightly
Not here (the Netherlands), everything is monthly, both pay and bills.
Same in Hungary. Not a single person I know gets their salary weekly or biweekly. It's absolutely not a thing.
Also, your bills are monthly. You mortgage is monthly. Your credit card bill is monthly. Preschool is paid monthly. Everything is monthly.