The problem with unlimited vacation is that the majority of engineers never have the guts to ask for it, just like they don't know how to negotiate. Unlimited vacation is a benefit for the company not the employee. It avoids taxes and complications due to carryover constraints.

To clarify, unlimited vacation is the company policy for all US employees. I'm just saying you don't need to work at a startup to get 6 weeks PTO.

Unlimited vacation is in no way the same thing as 6 weeks of actual vacation. Look into it a bit more. You'll see that unlimited vacation is really just a scam. In your case it's worked out. Actual vacation days are tracked and part of your salary. For example, if you leave, you are entitled to the wages of your remaining untaken vacation days. Unlimited vacation is a favor that your manager is granting. The company is not obligated to grant your request. You have no legal right to take the days off as you do with real vacation.

I do understand the difference, thanks. I think the degree to which it's a scam depends on the employer. Some say they have unlimited vacation and then the work culture discourages using it. Fortunately, that's not the case where I work.

The other benefit of not-unlimited is having it paid out when you leave. But if I had 6 weeks a year PTO, I'd just use it all anyway, so the part where it gets paid out isn't a big deal to me.