While I agree running for the most important post in the US, if not the world, candidates should be heavily scrutinized... but fairly. I don't see a lot of scrutiny of Trump. Having been in the real estate business, developers have a lot of skeletons in the closets. I am amazed media is not having a field day looking through his history. But I guess rating is more important than scrutiny.
Regarding the Ben Carson media flap: Had Obama's background been investigated with the same journalistic investigative zeal, I doubt that he would have been elected at all assuming that the left wing mainstream media would have reported the results of such investigations accurately, e.g., all the sealed records, his affiliations with known leftists including Bill Ayers and particularly Frank Marshall Davis, etc.
Even if there is some questions regarding statements in Ben Carson's biography, they pale in comparison to Hillary Clinton's lies about dodging bullets when she arrived in Kosovo or her pushing the false narrative about the video causing the Benghazi attacks and murder of 4 Americans.