[icebraining]

That was valid before cellphones, nowadays I expect people to call/message if they're late. I suppose that reading Fuxy's post literally implies that no such exception is allowed, but I assume it's not meant to be an inviolable rule.

[untog]

Don't move anywhere with an underground subway system then...

[icebraining]

Our underground subway system here in Lisbon has cellphone coverage.

[gcr]

Lucky! NYC's subway has complete radio silence.

But people in NYC know that the late party might not have cell phone coverage. Conventions adapt, life goes on.