Yes, I googled this and you're right.
It's interesting and raises questions for me. In the UK dry aged beef
always has the number of days it has been dry aged on the label eg "30
day dry aged", "45 day dry aged". The longer aged it is the more
expensive it is and hopefully better.
I've never seen lamb described as dry aged, only salt aged. And I've
never seen a number of ageing days on salt aged lamb. Further googling
indicates that salt aged poultry is also available - I guess that's
almost the same as when we killed a chicken at home, it was always hung
up in the shed for a few days before eating.
By complete coincidence I bought special bags for dry ageing meat which
were delivered yesterday. I'll start a new thread on that since it
could wander off what we're talking about here.
Malcolm