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?
I don’t get paid once a month. I get paid every 2 weeks.
At a prior job, I got paid every week.
Yearly is a good baseline, and also helpful for taxes (which Americans have to do by hand because of tax preparers lobbying against the government doing it for us).