Except for actually discovering those secret agreements, what policies do you see an union instituting that would ameliorate that problem? I see how unions can help set minimum wages and conditions for their members, but that's not what we're talking about here.
Collective bargaining for better wages and working conditions is part of what got us a step up from the world described in Upton Sinclair's The Jungle. It took 30 years, but did you expect it to get fixed quickly and easily? Politics is a lifetime grudge match. The Capitalists you sell your labor to, ideally, want you to work for free with perfect efficiency 24/7/365. That's why they are replacing workers with robots.
Anyway, a professional organization will give you more far flung networking opportunities as well as intelligence on what's going on at other firms, which will increase your value as a worker, and presumably, your pay.
