Work to rule can be differentiated from a lazy workforce if it’s done well.
Typically, work to rule is used to highlight specific bad rules, regulations, or enforcement practices at a company.
Say a company expects employees to do non-rule “glue” work to keep the company functioning. But, randomly and capriciously the company punishes workers for doing this “non-rule” work. A union can then announce that they will only be sticking to the letter of the rules until either the rules are changed, or the arbitrary and capricious enforcement of the rule is changed.
It can also be a rational response to a company that follows "management to rule". For example, I was once on a team where almost all of my time was spent coordinating with other teams and helping other developers instead of developing myself. When performance reviews rolled around I was told that none of that stuff mattered; only the number of tickets that I completed matter.
So I switched my focus to completing tickets. A few weeks later I overheard my manager complaining about a breaking change made by another team that I had previously been coordinating with: "Why is this happening so much? We didn't used to get surprised by these sorts of problems."
This is super common in engineering organizations. Any shop with a standard performance review will have a "score card" where your contributions are summarized in a method that can be compared to others.
Being a great team player can't be quantified, and gets dropped.
I often advise teammates to follow destructive rules by management to force management to overrule or cancel rules. The employee has cover for following the rules vs breaking rules set by management to meet goals set by management.
Typically, work to rule is used to highlight specific bad rules, regulations, or enforcement practices at a company.
Say a company expects employees to do non-rule “glue” work to keep the company functioning. But, randomly and capriciously the company punishes workers for doing this “non-rule” work. A union can then announce that they will only be sticking to the letter of the rules until either the rules are changed, or the arbitrary and capricious enforcement of the rule is changed.