Your family might have grown up with single presents on Christmas morning, while your neighbors had enough presents that they must have started wrapping over Thanksgiving. While, across the street, the folks with the menorah in the window may have spent every Christmas morning cleaning the house before going out for a movie and Chinese food.
When we're growing up - and when we're grown - we sometimes forget that not everyone celebrates the same holidays. And it's not just religious holidays that can get this way.
Consider the recent trend for stores to be open on what have, traditionally, been "no shopping" days - such as Thanksgiving or the Fourth of July. It used to be that you could safely assume that the entire family would get together on such holidays, but now there's a good chance someone will be working.
(And, yes, there are some industries - from convenience stores to hospitals to newspapers - where people are always at work. I'm not leaving them out - I'm just working toward a point.)
We all have our own frames of reference when it comes to holidays. And those points of reference color our expectations.
As a writer, you need to consider that when you're crafting your story: Would your main character refer to the holiday you're referencing? And - more importantly - Who is your audience, and do they have the same frame of reference as you?
- Does your reader know when Ramadan is? (Or does he think it's a hotel chain?)
- Would your Aussie main character actually know when Memorial Day is in the States?
- Would your characters celebrate Mother's Day or Mothering Sunday?
- Will your reader know whether Passover is more or less important than Hanukkah? (And will she have a preferred spelling of Hanukkah?)
This kind of attention to detail can truly make or break an entire story - even if it's never overtly mentioned in the narrative. I highly recommend working it out early - talk to a writing coach or an editor if you need help.