Because logically, it isn't. Nothing that takes scarce resources to provide can ever really be a "right" in the sense of "right to speech" or "right to religious beliefs." Those are rights that cost nothing to exercise, but something to protect in an imperfect state. But in an ideal state, they'd be true no-cost rights to anyone who is breathing. But "healthcare" is a right that costs something to exercise even in an ideal state.

Just use a reductio ad absurdum to think it through. A dangerous AIDS like diseases spreads rapidly, killing people all over. The only cure is a pill made of 10g of gold per dose, and you need to be on the 3 doses a day for a year to be cured.

There simply isn't enough gold to go around.

This conclusion of course, means absolutely nothing. It is not an argument against universal healthcare.

The "right" framing is also not true of high school. It too is based on a scarce resource. There is always an asterisk with a footnote indicating what the limits on the "right" are.

I personally think the citizens of Planet Earth would grow up into adults a lot faster if they gave up applying the dumb "right" framing to things that cannot conceivably be rights in any philosophical sense of the world.