Nurses have been underpaid for a long time.
I think there are two aspects to the problem. In the past nursing was seen more as a vocation than a profession - the sort of job people did because they cared rather than because they wanted to make a lot of money. And the result was that they didn't make a lot of money. Then came the nursing degrees and the people who didn't want to clean up fresh vomit because they have a degree and didn't spend years studying in order to clean up after someone else. But by its very nature nursing sometimes involves cleaning up after someone who is sick.
I'm not sure how heavily unionized nurses and ambulance drivers are. Sometimes government funded union jobs are the kind of thing where people get paid silly money even if they aren't doing anything useful at all. Nurses and ambulance drivers are kind of important, so it's curious they feel the need to strike for a better deal.