I don’t know, we’d need an official Anker response but I can guess. My guess is it relates to the size of the economies of various countries. The UK has a unique mains plug which would mean the development cost is spread across fewer deployed units, so I’d expect therefore to focus on the most popular product types. Then Anker heavily relies on Amazon so some of these issues will be created by Amazon’s distribution limitations.
I pond hop between USA and UK and so what I tend to do is buy USA products and use in UK and less the other way round. I accumulate, usually from old laptops, the UK power cords and plug them into the 5-port Powerport 5 so I can move between countries with the cord. The only really UK specific thing is the UK version of the Powerport 2 pretty much everything else is highly country generic.
You have to pass local safety rules.
Then you have all the language barriers. English is the nearest to Universal but can cause offense if not a local language option.
I see on Anker’s website they offer 9 countries (USA, Germany, Japan, UK, France, Spain, Canada, Italy, China) although when I click on them I only see English and Chinese text, and if I click on products they then take to the local language Amazon site.