Does anyone have some insight into the large discrepancies between the number of deaths per confirmed case, across different countries?

I'd argue that Germany tests more than most, so they'd be an outlier. But it's not just that. Take the US compared to the UK, for example

It was the UK vs. US numbers that I saw in an article, and there was no mention of this discrepancy so now I'm curious. (Preferably replies come with sources on this one too :) )