I've said that a significant portion of the collaboration occurred in broad daylight. The most notorious part which did so was this:
“Russia, if you’re listening, I hope you’re able to find the 30,000 emails that are missing.”
Taken alone it is possible to see this as an innocuous joke. But it needs to be contextualized. Part of the context is Trump's likely knowledge at the time that GRU had provided the hacked emails to WikiLeaks, who were in turn releasing them. Another part of the context is the negotiations of the Moscow real estate deal. Another is the response that very evening by the Russian hackers to make new efforts to hack into the Clinton campaign.
Properly contextualized, we can see that some of the most important aspects of the collaboration between Trump and his campaign and the Russians happened in broad daylight.
And when Trump fired Comey he wanted the world to know the Russian investigation was why. He wanted Rosenstein to put it in his letter of explanation. He told Lester Holt. And he told Lavrov and Kislyak.
When something incredible happens in plain view we sometimes doubt our eyes.