Methinks someone's milking it

I noticed these milk bottles almost literally piled up outside our back door earlier tonight.

So I mentioned it to Vanessa (it's occasionally good to talk when you're married).

"Oh, " she said,  "we've got a relief milkman on this week. The normal milkman is away on holiday."

Ignoring why it was that she knew this particular fact, one other question did spring to mind.

Does our relief milkman not know what an empty f***ing milk bottle looks like?