> even the best city in the US is still relatively bad
Your parent didn't mention the "best city in the US" though? Per the linked table it seems to be Irvine CA at 0.72 per 100k, which would be below average in the UK or France.
Takes the American "unwalkable city" trope to the extreme - you can't even really bike there. People live in isolate subdivisions (gated, often) connected to the outside world by mega-arterials with 6+ lanes.
It's not surprising it ranks so low in murders - it's hard to get killed when you're only outside for the time it takes to walk from your parking spot to the shop.
Your parent didn't mention the "best city in the US" though? Per the linked table it seems to be Irvine CA at 0.72 per 100k, which would be below average in the UK or France.