Colorado has had these caucuses for the last 15 years. Trump was aware of it. Trump was also aware that the delegates would be chosen at the state Convention. Trump had the opportunity to attend the Convention and address the body. Trump chose instead to blow it off.
So yes, Trump knew. Trump considered Colorado not worth the effort. And now he and his supporters whine about the results like a bunch of Democrats.
Compare that with Ted Cruz who already had an organization put in place in Colorado last year. Ted Cruz was the first Presidential candidate to address the Colorado Convention in four decades. Ted Cruz deserves kudos for the work he and his supporters put into Colorado. Yet all Trump supporters do is blame everyone else for their failure to work.
Not exactly true. Until this election they’d always had a vote at the convention which was non binding but gave a sense of where the sympathies lay. Colorado was told by the national GOP that they could not have a vote at the convention and then not assign delegates proportionally. To me that sounds like the national party was asking them to have a primary. Instead they abolished the convention vote. Note: There were lots of Trump delegates seeking support in the room. It is not a winner take all state. It seems rather improbable that not one of the many Trump delegates in the room was not chosen if the process was not rigged.
If you cannot see how the system in place at least looks corrupt and dishonest, especially to people that were new to the system and how they might legitimately feel they’d been cheated then I don’t think I can explain it to you.