The “privatised companies” had such short contacts that what they risked losing by standing up to the unions is a lot more then they stood to gain. After all, it would be the next company that took over the services a few years later that got the benefits. Most of the union activists retire on a good pension in a few years time, so don’t care what happens to the railways long term.
However the union have done 100% what they members have paid them to do, therefore I can only say “well done” to them…..