At the end of the day, politics is theatre, and little more, at least here in the US. I'm not surprised to hear this at all. All politicians lie. Trump is just better at it than many others. Most Americans are dumb or at least not known for their critical thinking - and will often vote for a candidate simply on their appearance/rhetoric, or because they're simply on "Team Democrat" or "Team Republican" without actually knowing most of their stances on major issues/policies. Though this election is a bit of an anomoly in that many (on both the left AND the right) were crying for an outsider because the political system and economy has been failing us for so long. The Dems foolishly decided to collude against THEIR outsider in Bernie Sanders to push their highly unpopular and corrupt candidate in Hillary Clinton while the Republicans ran with their outsider in Trump, which many initially opposed but ultimately ended up in a victory for them. If the Dems just let Bernie take the reigns and went with the voter's choice instead of letting super deletes and corporate donations determine the victor - the general election would have been a battle of the outsiders, from which I have little doubt Bernie would have steamrolled the election as he had the Blue Wall/Rust Belt. But I digress...
Trump is a performer (it's no coincidence he's appeared on WWE) and knows how to capitalize on trends with his rhetoric, and says what many want to hear. Simple as that. Obama was in many ways the same with his articulate/intellectual manner as a contrast to the bumbling idiot George Bush, driving home the point of "change" in the latter months of the stagnant Bush years back in early '08, promising a brighter future from the warmongering and authoritarian policies of the Neocons. But at the end of the day, it's about performance. On Trump, the jury is still out from where I sit, but I do know the economy has taken a large upturn, which is a large reason many voted for him.. Politics these days are little more than a sales pitch and an advertising campaign to gain votes, and have largely been that way since the day of Kennedy.
There's also the element of being heavily under the microscope, which I'm sure is even more true here in the US. Every little thing you say or do is going to be monitored, recorded, retained, etc. So it's easy to contradict yourself. After all, presidents are only human, and all people lie and/or contradict themselves frequently.
"We hold these truths t-be self-ful evident. All men and women created by the.. Go-you know the.. you know the thing!" - Joe Biden