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?
Many people in the US are paid every two weeks, which means some months you’re paid more than others.
Yearly has become standard as is hourly rate, because one is useful for taxes and the other is often directly negotiated.
I’ve been paid every week, every two weeks, and twice a month (first and 15th or 15th and last).
I work OT as well, and it’s feast or famine. I’ve had 30% of my yearly salary come from a little over two months where I worked 12/7s. Hourly rate doesn’t really get that across.