Indeed, in those case the duty of care was explicitly (legally?) delegated to someone else. Someone in the chain of transmission had a duty of care, and failed in that duty.

> Despite having obvious signs of illness, the Maplecrest employee went to work that day, and the next.

It wasn't a partygoer. I'm fine with holding specific people responsible (even legally) if they failed their explicit duty of care, but assigning blame to the whole population just because they don't comply with your narrow moral senses is intellectually dishonest. If we stopped doing that, maybe we could also focus on actually being effective (e.g. specifically protecting the old / vulnerable & their caretakers with specific, targeted and (most importantly) effective measures), not just requiring that everybody abide by arbitrary rules.