We have antitrust laws in the US but they do us absolutely no good when the government refuses to even consider enforcing them, which seems to be the case in the past few decades.
You mean via executive order? That's not exactly passing a law.
As if the will of the people is what matters... Only if those people are backed by money does matter. I don't agree with that, but that's the world we live in.
And proportional representation is found in the House of Representatives. We have a bicameral legislature.
An extensive study [0], showed "Basically, average citizens only get what they want if economic elites or interest groups also want it"
They studied actual attitudes about issues, moneyed attitudes, and tracked what got implemented as laws. NONE of the 'thinking, protesting, commenting, of demanding' was effective. MONEY was.
[0] https://www.vox.com/2014/4/18/5624310/martin-gilens-testing-...