Unlimited vacation was actually pioneered in the U.S., and spread from there. Most famously popularized by Netflix in its early days, but popular in law firms before that.
https://www.reddit.com/r/ExperiencedDevs/comments/nq2ph2/i_r...
https://www.reddit.com/r/ExperiencedDevs/comments/nq2ph2/i_r...
It isn't if they are meek or mid.
In general: it's good to let your employer know that you value your time. If you don't suck, they'll respect you more, not less.
I assume if you took the UK legal minimum of 5.6 weeks for example, you would get fired.