Much like the UK where 1/2 the population are on a months holiday yet it doesn't make a blind bit of difference to most businesses

Going slightly off topic, Boston was mostly shut on Xmas Day. Chinese and Jewish eateries opened at lunchtime and prior to that, the odd coffee shop and convenience store.
Few places open at the railway station but a lot shut.
Buses and the Metro were running to whatever timetable even in the snow. Didn't have too much of a wait on some lines but more on others.

Whilst spending Xmas in Cairns, some of the eateries were open near the ocean but that seemed to be it. Lots of families etc. having barbeques etc.

Suppose there's variations everywhere depending on who celebrates what.
As said above, Chinese restaurants opened on Xmas Day but might be shut for days around their New Year.

Airport wise, it's just a case of making sure public transport is running, should it be required. Most things will be still open and whilst it might be quieter than an average day, it's surprising how many people are travelling.