I still believe that Iraq (Hussein) did have a stash of WMDs. I also believe that he was adroit enough to move them before the American forces entered. Can I prove it? Not at all. But I do believe that the absence of evidence does not equal the evidence of absence.
Mexico would pay for the wall if it had been allowed to get built although not in the way that phrase was understood by liberals. It was clear enough to most thinking people that Trump meant that they would effectively “pay for it” as a result of his proposal to renegotiate NAFTA.
The effort to repeal and replace the misguided ObumblerCare program got stymied. That doesn’t mean the campaign commitment was a lie.
But as to your last sentence, yeah. Both sides have been exposed as engaging in the long standing practice of lying. They seek their respective Parties’ core for their primaries by pandering to the associated more extreme sides of the political spectrum. We know they then cynically “move to the middle” after winning their primaries because the general campaign winning isn’t achieved by just their more extreme base. It requires something more moderate, especially if they desire some crossover voters.
The foundation for allegiance to a political Party isn’t in what they “say.” It’s in what they try to DO.