A quarter of British people are now drinking non-dairy milks

[Beowulf]

I agree.

Is anything other than animal milk allowed to be called 'milk'?

The EU decreed in 2017 that the terms milk, butter and cheese (amongst other things) could only be used to refer to products derived from animal milk.

Exceptions were made for coconut milk, almond milk and peanut butter due to precedents showing they had been in use for centuries.

I'll try and find the article, I read it again recently when researching something else.

EDIT:

BBC News - EU court bans dairy-style names for soya and tofu
http://www.bbc.co.uk/news/business-40274645

 

[Steevo]

And one more thing, why do they call plant juice milk? it's nothing of the sort.

It’s not even juice...!

It’s just blended nuts and water.

 

[Roger Perry]

Someone using water to milk cows in the West country cannot possibly be compared to someone in California using copious amounts of ground water to irrigate almond plantations. Let's call a spade a spade eh?

Except when you are growing any type of nut producing tree or vine in California, (or anywhere) the drip system installed to feed them is controlled to the last drop, the tech involved will take account of prevailing weather/temp/humidity/growth stage to ensure no over or under watering.
I do know a little about this as on our New Mexico operation we are growing 750 acres of melons/cotton/onions all on sub surface drip.
Water is a valuable commodity across the west, even here in Colorado under pivot irrigation we are using soil probes to speed up/slow down our pivots. With ever more of Americas' population wanting to live in Western states, any water rights a land owner has become increasingly valuable, cannot afford to waste it..

As they say............"you buy the water...we give you the land"

 

[PSQ]

From the Alpro Oat 'milk' website:
INGREDIENTS
Water, OAT (10%), Chicory root fibre, Sunflower oil, Calcium (Tri-calcium phosphate), Sea salt, Stabiliser (Gellan gum), Vitamins (Riboflavin (B2), B12, D2)

So it's somehow allowed to be called Milk, when in reality it's an emulsion of water, oat flour, fibre, vegetable oil and salt. The next 2 are interesting as Gellan gum should be labelled as E418, and tri-calcium phosphate which should really be labelled as E341 but that doesn't sound very 'vegany' does it, so perhaps Alpro forgot
Mmm!, all the fake dairy goodness of a product every bit as synthetic and 'corporate' as Coca Cola. But what do I care, it's all great for the oat market