HSA requires a high deductible health plan, not everyone could afford that deductible.
"To contribute to an HSA, you'll need to be enrolled in an HSA-eligible health plan, also called a high-deductible health plan (HDHP)."
"To contribute to an HSA, you'll need to be enrolled in an HSA-eligible health plan, also called a high-deductible health plan (HDHP)."
[1]: or so it seems, I tried to figure this out earlier in the year and the data is just lacking in order to make a perfect decision.