Musk was taking 20 minute flights in his jet to go to the beach - insanely wasteful because the fuel overhead of startup/taxi/takeoff and landing/taxiing is extremely high for the distance traveled. It's about the most environmentally damaging, wasteful way you could possibly move yourself from point A to B.
At least Swift's flights are often very long distance, and she has several major reasons for using the private jet; because of how large and obsessive her fan base is, it would be beyond difficult for her to travel via non-private commercial travel and a huge annoyance to anyone else on the plane. There'd even be fans and paparazzi trying to predict what flight she'd be on and booking tickets themselves.
There are also security safety concerns, although they have to be weighed against the much higher crash rate for bizjet travel than commercial passenger aviation flights.
She also has to physically travel for a tour. There's no other option.
Musk can do 90% of what he does via videoconferencing or phone calls - and from stories that have come out in the press from former executives who worked for him, he incessantly calls his subordinates, even in the middle of the night.
Still, people are missing the true motivator behind this legislation. It's not just about the rich 0.01%'ers. It's also about all the FBI, DEA, and CBP planes that are registered through shell companies to somewhat hide their purpose...but ownership and purpose becomes obvious when you see the model of plane (the agencies have their favorites), photos of it by plane spotters (showing obvious surveillance equipment pods), and the flight paths available online (usually endless loops over an area, or loops that follow a track from one point to another, obviously following someone.) This makes it somewhat harder to track them.