Oh, how familiar this is indeed! Just can’t stop looking.
This is very likely to be already advanced girls since standing on toes is far not the first element to be taught. And the simplicity of doing it (as well as everything else in ballet) is a result of days, months and years of damn hard work.
The points are helping, of course, but there is a lot more involved. From stretching and balance to co-ordination and fitness. We took it is a holiday when we were allowed to grab a snack or a burger.
Next time you see ballerinas – remember that. And do pay tribute to their efforts.