Hell, I’m from Canada where we have (mostly) socialized medicine, and the one time I made a claim on private insurance it was denied. That was after I had called them to confirm that yes, my policy (should have) covered that expense.
And it was only a few hundred bucks too, so my frustration was more about the principle of the thing rather than the cost.
I fully appreciate that, and it’s the same in Canada for many people. I’ve witnessed it personally. I’m very fortunate to be in a position to handle that sort of thing.