Ash trays in the toilets are indeed a continuing regulatory requirement; if some buffoon does light up in there then you want somewhere safe for them to dispose of it. The LAST thing you want out over the ocean is said buffoon sticking their smoldering cigarette end into the paper towel unit and starting a fire.

There are still odd passengers, not necessarily English-speaking, who think it normal to have cigarettes in public.

Regarding ISO compliance, if your procedures require nonsenses then you haven't got your procedures done sensibly, a bit like no Health & Safety regulations prescribe the over-the-top placarding you sometimes encounter.