Emergency services, NHS, taxi drivers, breakdown, people monitoring phone/broadband/electricity networks will all have people working on Christmas and Boxing Day.
Perhaps non-drivers would like to be able to get home from where they celebrated Christmas in time for work on the 27th.
Or non-drivers have split families and need to divide their time.
Or people who don't celebrate Christmas want to get to work.
You are welcome to take any of the other 363 days of the year to rest and see your family!
I 100% agree with this. And while I understand that most do cocoon on Christmas Day, Boxing Day is no more sacred or special than Easter Sunday when services run at a limited service. It also has huge sales. Do we really want all of these shoppers driving?
Flights run on both days. And workers staff the airports and planes. And many travel. Should they all drive too? Or should we ground aviation?
I would add that Boxing Day is one of the largest football and horse-racing days of the year - the latter especially was historically very well served by railways.
Our exceptionalism on this is crazy. Australia, the United States - all have some semblance of public transit on Christmas. We have so many tourists too, and hotels/pubs do indeed open for many - not to mention those who don't celebrate, those alone/freestyle, more complex family set-ups and blends which require movement, and most importantly, those who have to work.
Let alone comparing ourselves against the European countries which are basically closed on the average Sunday still have service, whom we mock for not being able to shop on Sundays, other than in railway stations or Le Marais!
You don't go into medicine or the police force thinking it isn't a public service, and that what you do doesn't need to exist 365 days a year. I don't think people should go into the railways thinking differently either. I would bet there are enough non-celebrating (or nonchalant / happy to take money) - staff who would take some extra cash and days off to do so. Much like every other industry.