I work nearly every holiday and do so by choice. I'm an empty nester, the pay is fantastic and I work nights. If I choose, I can forgo a bit of sleep and be around for the celebration, so it becomes a win-win.
When a customer (call center) says "I am so sorry to call you on this holiday, but..." my go-to reply is along the lines of "That's what I'm here for. Happy to help!" then move the conversation along. To most people's credit, the vast majority do have a legitimate, pressing concern that needs to be addressed right away.
The only times I really get frustrated is when someone makes the comment, then proceeds to request something that totally
could have waited until business hours or at least the next day.
And before anyone gets on me, I realize that it's my company (by marketing us as 24/7 seamless service from day to night, which isn't always true) who creates this issue and not the customer. Its not the act of them calling on the holiday for something silly, it's the fact that they comment on it (pity sentence) then go on to book some flight for 6 months from now. I'd rather they not comment at all about it, just tell me what you need!