I'm in a union and see similar things, but instead of using lawyers, the union would note that the contract had been violated, and management will typically agree to pay the people who would have done the work. If it's just 10 minutes, the union probably wouldn't bother with it - unless it's a pattern, and in that case, they'd add up all the 10-minute transgressions. I often disagree with the focuses of my union, but I'm still happy to support it. As many have noted, the main thing a union does is balance the leverage. Without them, the employer has all of it.

For seemingly silly rules like the ones you're describing, the union is attempting to protect jobs and hours.

I wish my union was more like some European unions I've read about, where they're involved in the decision-making process. Mine fights for wages, positions, and conditions, but management decides how things work - so long as they're not violating the agreed-upon conditions. I expect your workplace is similar. Instead of mapping out a path with management, my union reacts to the path set out by management, and I think a lot of the weird rules come as a result of reacting, rather than helping to create.

I also think this sort of collaboration would be better for companies, particularly larger companies, where there is a disconnect from how things actually work and how corporate thinks they work. We have this particularly terrible piece of machinery that corporate is obsessed with justifying. We have other machines that do its jobs better, but it does the jobs of many machines - just much worse. It just wastes a lot of time, but corporate incentiveses management to use it, and when discussing the POS machine, management cites those incentives as reasons for why the machine is actually good. When you say, "Yes, but how does wasting all this time using this particular machine help the company?" management highlights the incentives.