If you take PTO then you are supposed to tip 20% of your pay back to the person that is covering for you. Depending on the job some of the money might be shared with others.
I understand that in some Bay Area companies the rate is now 25%
I'm not familiar with the concept of unlimited PTO, only with the concept of PTO by law, by tariff system (unionised jobs) and by individual employment contracts.
German law says you have to have at least 24 days PTO, given a 5 day 40h week. It's common to have ~30 days PTO in most professions.
And of course you don't give anyone your money, the employer is in charge to organise that people can take time off. And sometimes this is done by having everyone off at the same time.
It is interesting to see the comment from the person in Britain with unlimited PTO. I've never heard of this in the EU/UK before.
They would need to use at least the legal minimum, which in Britain is unchanged from the EU minimum of 20 days.
(I once had a colleague who received a letter from HR reminding him of this requirement, recommending he take all 30 days leave at his preferred time, rather than doing nothing and being required to take the last 20 working days of the year off.)
I understand that in some Bay Area companies the rate is now 25%