In Ireland, it isn't only rural addresses which have no house numbers. Plenty of houses even in towns had non-unique addresses before the introduction of eircodes. On my road, all the original houses (each standing on an acre plot) have numbers, but all the infill ones don't. You'd think the house built on the corner of 502's land might get 502A, but no. When my parents bought this house, the address was the same as many many others on the same road. They gave the house a name, so it would have a unique address, though the previous residents had managed fine for twenty years without one.

I had friends who rented around the corner. They had to give their address as "care of" the landlord's name, though the landlord didn't live there. That's because An Post knew his name, but wouldn't know the names of tenants.