Public transport is for the plebes. Trump bought the 757 plane from Microsoft's co-founder Paul Allen and then slathered the Trump name all over it including a "T' on the tail. He bought it to replace his old 727. Out with the old jetliner, in with the new jetliner as they say.
And, because he is a giving, thoughtful man, Trump made sure to mention that, "It's one of the quietest airplanes there is, I did that for the benefit of Palm Beach." That's a little dig at the FAA who Trump has been feuding with over the noisiness of planes flying in Palm Beach at his Mar-A-Lago club. He fought against the expansion of the local airport there, and for now, he's getting his way.
Recently, Trump got into a bit of trouble because his plane's registration was out of date as of January 31st. The FAA can either fine or assign other penalties to the owner and/or operator of the plane. In addition to his plane, Trump can also count three choppers in his lineup of aircraft.