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?
In France, people are sometimes paid 13/14 months a year. It means you get two months as a bonus, so it’s relevant in this case to tell the yearly salary