The other owners know it, but why would they care? There is already a mechanism in place that specifically addresses the union's concern, and every time the union has made a complaint about the Pirates it has not held up under the rules in place. And if expanding those rules to force the Pirates to spend a little more is something the union desperately wants (and they may very well), then the owners are going to demand some other sort of concession from the union to agree to that. Which is, once again, a win for the big market owners.
If the Pirates and the Marlins are forced to spend $10 million more per season on payroll that's a drop in the bucket compared to what the Red Sox and Dodgers and Yankees do. That won't affect them at all, but you can bet that the concession they get from the union in exchange for that will benefit them, because that's the way that it works.
Of course. I mean, the MLB players union hasn't really conceded much over the years, but it's safe to assume that's how it should work. But this isn't a $10 million problem. It's a lot bigger.