For an apples-apples comparison we would need to know exactly what the €8/month plan includes, and exactly what the $50 plan includes. Since we don't know either, it's really getting off the real point, which is that NHS is not expensive.
FWIW, you can get unlimited text/talk/5G for as little as $19 in the US, all-in, with a major carrier (Verizon.) That's the cheapest I've seen for a major carrier. MVNO carriers might have cheaper deals but not likely with unlimited data.
Is $19 a better comparison for NHS? 😀