When you put all the points on a graph and they form a line, what more "evidence" do you need?
Your request for evidence reminds me when the 3 telco operators in my country raised their prices simultaneously on the same day, and the nation's anti cartel watchdog said they found no evidence of price fixing lol
Just because the system is corrupt, incompetent or ineffective at finding evidence, doesn't mean there isn't collusion going on.
