In short, yes.
Part of their argument is that the company should accept any increase in costs or reduction in % spare capacity as they have a higher % spare than industry norms and they have benefitted from the goodwill of drivers for so long.
As it stands, indefinitely.
Also as it takes around 18 months - 2 years to recruit train and assess a new driver till they can drive on their own and are "productive" what would recruiting more drivers now achieve? And as TPE are out of franchise and in Direct Award, all the purse strings and top level decision making will be made by the DfT anyway. And how far do you go, how many spare men do you have each day at each location to cover for every possible eventuality at all times of the day all year round?
My view is that it has got sod all to do with the Union as to whether individual drivers work their rest days ot overtime. If they want to (and many do, and aren't overly fussed about 156 rest days) then why can't they?