You can cover Sundays and Bank Holidays without making drivers work 7 day weeks, just like other industries with round the clock service.
And while it's not necessarily the case in this part of the country, there are many people in this country who do not celebrate Christmas and would be happy to work, that day. One of our local convenience stores, run by people who don't celebrate Christmas, makes a small fortune, that day.
Though, currently, we can't staff the hours we do need (collectively, not just bus drivers) so no chance of making big changes to operating patterns.
RE: Bank Holiday