The key is you don’t pay for healthcare expenses with the HSA, but instead pay with after-tax funds and save the receipts. Later (many years later), you can take out the HSA money and spend it in retirement tax-free (up to the cumulative amount of medical receipts you’ve paid and accumulated).
Used this way, it’s a retirement account (one with hands-down the best tax treatment), not a health care savings/spending account. To get it you have to have a HDHP and cover the expenses along the way.