The main beneficiaries of the UK imposing extra red tape on prospective language students are Ireland, Malta and the United States.
Hmm. So what's this about?
googles
https://www.gov.uk/government/news/insecure-id-cards-phased-out-as-travel-document-to-strengthen-uk-borders
From today (Friday 1 October 2021), most EU, EEA and Swiss citizens will need a valid passport to enter the UK as the government stops accepting national identity (ID) cards as a travel document.
These ID cards are some of the most abused documents seen by Border Force officers and, last year, almost half of all false documents detected at the border were EU, EEA or Swiss ID cards.
They can be easily abused by people attempting to come into the country illegally and by stopping accepting these forms of ID, the government can prevent organised criminal gangs and illegal migrants using them to enter the UK unlawfully.
I mean, I assume that most people in the EU have passports.
And while I can imagine that Malta or Ireland, both EU members, might be fine with using an EU ID card to prove identity, I'm sure that we in the US aren't, any more than an EU member is going to let someone from the US in if they just show up with a state driver's license (the closest analog we'd have to a national ID card).
There was a point when we and Canada used to let people from each other's countries in just with just driver's licenses, but that was ended as part of the post-9/11 security changes. Gotta have a passport (or equivalent) now.
Also, a lot more Americans have passports these days. Used to be quite unusual, like, single-digit percentage of the population not many decades back.