Just to round off what I was trying to say regarding NHS staff / railway staff.
The reality in the NHS is that generally the staff in on Christmas Day/ Boxing Day are those involved in continuing care (ward staff, care staff, some community staff) or in emergency care (ambulance staff, on-call services, A&E ... and midwives

). What is termed "elective" - planned surgery, GP appointments, outpatients certainly don't feature on those two days.
On the railway a lot of staff
will be in over the Christmas period - engineers, certain signallers (to get engineers' trains to and from site), loco staff (ditto), on-call management etc etc But should staff be
required to come in so people can get to shops, or football matches, or to visit relatives?
That - surely - is the distinction.