My uneducated take here is based my my friend's experience, who is an electrician. He's happy to be more flexible than the law allows him to. Work more hours, longer shifts, worse times of the day. Whatever gets the job done as good as possible. But there's an expectation of mutual respect here. If the boss starts not compensating him sufficiently for the work he is asked to do, not giving him time off and periods of calm, and listening to him when he thinks he's nearing his limits, the system doesn't work.

Just like laws in reality are the to protect the average Joe from an abusive employer, unions are similarly a strength in numbers approach to being treated better.

It seems unionisation is one way people slam the breaks on companies that don't treat them fairly for the effort they are expected to put in. Your evidence seems to indicate the companies had plenty of chances to ask "why are people unhappy" before their employees unionised