Strangely, when I was working for HBOS, officially The Worst Bank In The World and in its death-throes with mass redundancies, loss of bonuses, staff losing fortunes in shares etc... All through that they retained a mostly good relationship with the unions. I had my union rep on speed dial in the runup to my redundancy due to lots of localised nonsense, and it worked like a dream version of employee/union relations:
"Hi, this is Northwind again, some obvious bullshit has occurred"
"Yes, we agree that is obvious bullshit. Leave it with us"
and they would speak to their guys, and their guys would speak to some other guys, and within a day or two, a senior manager or HR person would phone up my boss and resolve the bullshit, usually by virtue of saying "that's obvious illegal bullshit" or "that's the sort of obvious bullshit that will see us get butthurt in court"
Now, sure, the unions were also generally agitating and trying to defend workers' corner in a total losing situation but HBOS mostly didn't seem to lose sight of the fact that there's shared interests, and worked pretty much hand in hand with unions, partly to keep people as happy as possible and partly to avoid needless disputes, bad PR and court cases. And they basically seemed to get the fact that when the unions disagreed with them, there was a reason for it, they weren't just being awkward. In the environment of the time, and with a general environment of hopelessly incompetent and demoralised managers and middle managers, it was a massive deal. Possibly the only thing I ever saw them do right.