Valid point, I lost track of the freelancer situation.
As for the differing costs of insurance outside of the freelancer world, I've found the costs in the US can vary wildly. Those tax boxes aren't the only way / shouldn't be the only comparison for US healthcare costs.
I don’t understand why they can’t be used to reasonably estimate healthcare costs. ACA compliant plans are pretty standardized, as well as the metal levels indicating expected healthcare costs.
Some plans will cover some providers and some won’t, and rural areas will have issues with even having providers at all, but for most major urban/suburban regions, it should be comparable, +/- 10%, even 20%.
Either way, you know that healthcare costs are in the thousands and $10k+ per year per family, which is a lower bound you can add to calculating US tax rates.
As for the differing costs of insurance outside of the freelancer world, I've found the costs in the US can vary wildly. Those tax boxes aren't the only way / shouldn't be the only comparison for US healthcare costs.