The graph shows both public and private expenditure. If you only consider the public per-capita expenditure it's more than every other nation on the graphs public + private per-capita spending.

The data behind the graph is probably from OECD, which does not use a public/private classification. Mostly because in many OECD countries, "public" healthcare is largely funded by private insurance.

According to OECD data, US healthcare spending in 2023 was 28% from government schemes, 55% from health insurance, 11% out-of-pocket, and 5% from other sources. For most countries, the health insurance category is further split into compulsory and voluntary categories, but that distinction does not really exist in the US.

All US health insurance spending is reported in the compulsory health insurance category. Probably because the bulk of the spending is from employment-based insurance, which is effectively mandatory. (You usually can't opt out and take cash instead.) Naive aggregators then combine government spending and compulsory insurance and report that as public spending.