> people who grew up in developing countries or even in extremely rural areas of Western countries who grew up with water unsafe to drink before boiling it off will be even more skeptical.

I'm Brazilian. We learn early in school that water must always be boiled or filtered before drinking. I'd feel very uncomfortable drinking water directly from plumbing, no matter how much some people say it's safe.

Every place here (and I don't say that lightly, I don't think I've ever seen an exception) has either a water filter connected to the plumbing (for unlimited on-demand filtered water), or at least a separate standalone filter, or sometimes a drinking fountain which gets its water from large mineral water containers (and it's normally real mineral water bottled from real mineral springs, not that nonsense that is adding minerals to tap water and saying it's mineral water).

Edit: and IIRC, there's a law that bars and restaurants must provide filtered tap water to their clients without extra cost when requested. Even the law requires filtering.

Keep in mind that the filters most people use in Brazil mostly only handles dirt that accumulates on the water tank and keeps the water in a nice temperature. If the tap water had any contamination, those filters would change nothing.

It's still good to get rid of that dirt. If you live near a main street or some other polluted place, it can become harmful. But it's not that much of a change.