None of that gets you even close to 10% mortality. In any given year only a tiny fraction of the population needs advanced hospital care to survive trauma or other diseases.
You do not recall correctly. You have confused case fatality rate with infection fatality rate. There are a large number of infections which are never officially counted as cases due to limited testing and minimal symptoms.
Well, with that line of reasoning we cannot trust any corona statistics, can we?
Anyway, the effect of failing to "fallten the curve" in Lombardy are well documented. And this happened in December 2019 before we had a global pandemic.
Trust has nothing to do with it. Based on seroprevalence studies and other factors the CDC has estimated that only about a quarter of infections were officially counted as "cases". The undercounting was even worse early in the pandemic when tests were hardly available. So your point is not valid.
But that's US statistics, this happened in asmall area in Northern Italy.
Even if we go with your numbers, we get an average of 4-5% and since we know there was a huge spike in the middle of the outbreak it is not unrealistic to assume they were above 10% at some point.
And it’s not just COVID… if the hospitals are overrun many other things will have much higher mortality, like trauma cases.