This can lead to conversations like: "You've asked for N weeks vacation but policy is strict everyone starts here with 2 weeks". "I can probably live with that for an extra X k/year." ... "We can do N weeks".
I think in tech 2 week is becoming rare though. More likely either longer, or so-called "unlimited" (which itself is nonsense).
The more weird thing I find in US corporate culture is a tendency to not take the vacation you are allotted. In some countries this is legally at least problematic, in the US it's sometimes a badge of honor.