Those unionized workers, the ones that still have jobs, don't have the protection you imagine they do because those employment gaurantees were written out of the union contracts for every major industry in Canada over the past 15 years.
Most unionized workers in North America kneel down and pray every night, that they will have their job long enough to get their pension. As such, employees count the days to their early retirement qualification and get out as soon as they can.
It's become such a serious problem, that contracts being written now stipulate you can't retire early if the company designates your job as "mandatory position, unable to replace". The upside is that they are usually required to pay you a bonus, per annum that your are required to stay.
For CP Rail it's $50,000 per year, thats above and beyond your normal wages, overtime, benefits etc. and they routinely invoke that part of the collective agreeement until they find and train someone to replace you. If you happen to be really good at your job, they don't put a rush on replacing you so you may stay 3-5 years and bank a free $150k-$250k. Because the people that would get the $50k are in the lower end of the top tax bracket, they don't get stuck paying a higher rate.