Unions are important, as anyone who's ever been through any HR steamrollering will know. Without the representation and support of unions an individual worker has no ability to stand up to the weight of any large organisation. As someone who's been through failed stitch ups by management, the ability to rely on experienced people who actually know the law - not the law according to Company's HR department - and can accompany and advise you in meetings, they are invaluable. I've also used them to get huge discounts on expert accounting advice.
I probably could have done the research and learned some of the things a union rep told me, but I can't say the same for everyone who I've ever worked with. People are easily intimidated by lectures on "company policy" dressed up as legalese, they should be able to call on expert support when they need it and feel out of their depth.
It's not all national strike action, there's thousands of individuals who get support, but it doesn't suit to cover that in the Mail.