They should be the first staff to be sacked, or at least hauled over the coals, as those unable to get a doctor's note could be seen to be breaking the T&Cs of their contracts that they're so desperate to cling onto in the face of common (and economic) sense.

I was working at the BBC during am NUJ strike - any staff member who called in sick on strike-day lost a day's pay whether they were unionised or not, unless they could produce a doctor's note. No-one challenged it.

I really don't see how agreeing to fly a family to, say, Australia on 20th December then deciding you don't want to fly them back on 27th (despite they fact that their fares pay your salary) is any different to BA refusing to pay your expenses during a period when you have decided not to work for the company.