What Trump has done is to practically launch an independent bid for the presidency, using the Republican party as a platform.
He won't listen to the leaders of the party, he has disdain for politicians (including Republicans).
Question: why then would the GOP put up with something like this from the very start?
Certainly they could have stopped Trump in his tracks one year ago, by informing him that he is welcome to run as an independent.
Does it make any sense at all for noted, public, respected Republican leaders to complain NOW that Trump is not a true conservative, and actually does not represent the party?
Therefore, there is only one way out of this mystery: it was all planned from the beginning in order to achieve a certain goal.
No other candidate (democrat or republican), for the past 50 years, would have been able to make it past the first primary under the public's scrutiny, having to deal with the "Trump university scam" and the "tax returns issue". Yet, so far, Trump has been spared what would have been a devastating inquiry into his finances/business practices, one which would have spelled the end of a political career for any other candidate.