They are used in Finance, regardless of title, to help entice people to leave a competitor.

Almost everyone in this world works on a decent salary and potentially large bonus model for compensation. To help entice more long term thinking, and hold people to the firm, bonuses vest over 2-4 years.

It's extremely common to have a discussion with a potential new firm about how much money you are walking away from unvested bonuses and for them to just match that bonus number and vesting schedule as a precondition for joining a new firm.

As a new grad from CMU undergrad, every offer I had came with a sign on bonus (n=5). Size ranged from 5k at a smaller public company to 75-100k at a couple of FAANG companies, one of which I was a returning intern at.

in the bay area, pretty much every offer ive gotten has some sort of signon bonus. Sometimes it was labeled as moving expenses. Ive been in a postition with options at the previous company you need cash to exercise, or having to payback a previous signon for not making it a year. Or the equity in the new company has a cliff of the first year so it kinda covers that delay.

I think the real reason is its easy to say 'your first year cash comp is XXXXXX' and hoping the candidate doesnt realize that second year is XXXXXX*75%.

Small sample size, but in Austin I've seen 5k-10k.