I didn't read it either but its a simple result of economics and human nature. Payroll is a % of a business and a company really doesn't care so much what the breakdown is just what the % of the total payroll is to revenue/profit/etc.

In collective bargaining the workforce determines how the total pot gets split largely. This generally leads to inequality with the top earning disproportionate to the bottom. The easiest way to reduce payroll from the management side is toss the existing workforce a bone in exchange for a B scale, scope, work rules, etc. Companies take the long focus as to what will drive savings over years (you can amortize a B scale and project savings immediately). Work groups focus on their needs which is generally only a 20-30yr window at best and in reality focused mostly on the current contract and what is in it for them. End result is everyone on property when the contract gets signed earns, the new guys pay for it (i.e. the old paying your dues). The company gets their savings a couple years later when the new scales start to take effect or through ability to outsource work to cheaper options and it tends to be exponential as the time goes on (i.e. see current state versus 30yrs ago).

It isn't ever going to change but it is always fun to talk about.