Citation needed for that. (And by world leaders do you mean politicians, or wealthy people? Many world politicians have other reasons for avoiding the US.)

There isn't much motivation to release such data to public, those affected know this very well, rest shouldn't care (according to them). From living in Switzerland for 9 years and having fiancee as a doctor I can tell you it is at least somewhat true, nobody here bats an eye if some powerful person is treated in hospital across the street (or more likely private clinic in some nice place).

There are many reasons - high quality of medical staff, top notch equipment, just a good place to be. Also, Suisse is long term perceived as creme de la creme in many aspects of life, so this fits the overall picture, be it real or some wishful thinking (mostly real though).

Even if there is citation here, would this data around super wealthy people be of use for public health?