Buying the conditions off people is the only realistic way of achieving change - at least in any meaningful timescale. I’m not sure the “price” would necessarily be that high, where I am people squabble over paltry amounts of overtime after all! Bung in a couple of extra leave days and most would be happy.This isn't really economically or operationally viable. You are basically asking the union to name it's price and giving no incentive to make this realistic. Costs could easily run into the tens of thousands per employee. Where should that be recovered from and is it really a good use of very limited resources?
There is then the high likelihood that unions will come back with higher and higher demands each time if they feel there is a good chance they will get what they want. Or alternatively even if they don't get what they want unions may just adopt stalling tactics in order to hold up the franchasing process each time there is a new contract.
The bigger problem is the substantial increase in drivers, both financially and the logistics of providing them. All of a sudden one goes from a 6-day roster to a 7-day roster, or equivalent, with a whole load of extra duties on the roster. They have to be covered one way or other, so you either have uncovered duties galore (probably on the other six days too) or else a requirement for many extra people.
In a way it’s a perfect storm - drivers salaries have increased such that RDW is less valuable and a drive to cut costs, all at the same time as a desire to increase Sunday services. Something has to give...