His political appointee runs the DOJ. He can't close Guantanamo unilaterally, but he could have done a lot better on civil liberties.

Or he can be just bad at leading changes.

Or the US has a weak political system compared to multi-party systems in better functioning democracies, such as Canada.

The political system was designed from the beginning to be weak based on what the founders had left. A very specific set of powers granted to the federal government but split between three often opposed branches. The remaining power defaulting to the states but still separated by largely the same system of checks of balances, and often with the two systems (state/fed) themselves opposed.

The system was never designed to be one where you could implement massive changes overnight.

Controversial politicians, by their very nature, are not convincing liars.

If you want to find examples of convincing liars, you need to look among the people who are universally loved.