I think it depends, having worked in retail, boxing day is miserable working.
You have to be in the shop till god knows when Christmas Eve to start setting up for the sales and then get in at whatever time in the morning on Boxing day to finish up, only to be generally abused, shouted at for ruining someone's kid's Christmas because a toy didn't work, while the next customer comes along to tell you its such a shame that you are working.
The retail businesses I have worked in, only open on boxing day if it is profitable, customers don't go to it, they wont open.
As such as a personal choice, I will not go into business on Christmas day or Boxing day as I don't agree with it.
But, there are going to be people who don't celebrate it for whatever reason, businesses with people who don't celebrate and they will want to open and as long as the staff are happy to be in, than that is great, but knowing the hospitality sector I bet alot of staff are faced with work or dont come back.
As for comparing hospitality to any of the emergency services, that is very different and a really stupid example to make, you are not going to die from not eating out for one day.