> Sure, but most tech companies will give you them anyways
I've yet to see any private employer in the US that gives employees every public holiday applicable in their jurisdiction; heck even public employers often don't, as federal government doesn't give state holidays in the location and state and local agencies often don't give all federal holidays.
> There are only ten federal holidays. If you are working in the states, you get most of not all of them.
MLK, Washington's Birthday, Labor Day, and Columbus Day are particularly frequently not granted by private employers. Columbus Day and MLK are each not given by some nonfederal public employers (to my knowledge, a non-overlapping set.)
I know from previously working there that Microsoft gives all public holidays. When I started you had floating holidays you could take for some (MLK, Columbus etc) but now all are given. Wouldn't be surprised to learn it's the same at Google, FB et al.