The 2 party system isn't enshrined in law but because it's been so entrenched for so long, it seems to be de facto law.  The example you mention about the street vendors is what is referred to as the spirit of the law vs the letter of the law.

I wouldn't call the parties outside of the major 2 simple.  It's just that it simply take time and lots of $$$ to establish a real foothold and then after that establish a true presence.  

As a lawyer, I can tell you that only a court can establish a violation of the law. And until a court decision is reached, Binance hasn't violated anything de jure.

Binance isn't going by the letter of the law and playing it safe here for sure. They want business to continue at any cost.

Actually, there have been plenty instances of this already with the current administration- see James Comey, Ras Baraka, Letitia James, etc:  "If the government starts initiating criminal and administrative cases against undesirable politicians and activists and jailing the most prominent representatives, then in my opinion, this could be coercion, but so far we haven't seen that."

"People are often dissatisfied, but if they are dissatisfied, no one is stopping them from organizing their own party or running for other political office in their state. In the US, state laws sometimes vary greatly."  People have run for office due to dissatisfaction with the status quo and yes, even though small and usually doesn't make the news, a lot of states have upwards of 3 parties but the big 2 still dominate.