The alternative would be to admit underprepared students without offering any kind of support and take their tuition money until they fail out. That's no better.

Or, and you may be shocked by this, another alternative would be to make them take an IELTS exam, set the minimum score high and deny them entry if they don’t pass.

There are no such guarantees – as far as I am aware – and as a former student I remember having a single Chinese classmate in my 4-year Computer Science degree program. After the Foundation Year, students of all nationalities were treated equally, and there were much more 1st year students from the US and the EU than from China.

Also had colleagues from Vietnam and China who attended the foundation year. It was clear to me they couldn’t read/write English to a high school level. They still got in

It might depend on how competitive the general admission process in a particular university is. I wouldn't be surprised, if 70% of the Britain's 100+ universities accepted all Chinese applicants. In the case of University St Andrews, it has plenty of more qualified applicants from North America who pay the same as Chinese and, therefore, can afford not to accept them.

That is rather cynical.