Ah, so you are acknowledging that your previous post was incorrect.
In answer to your current posts:
I was already aware that US citizens had a unique tax situation, nevertheless,
people taking out UK student loans also sign a legal contract, with a contractual obligation to make repayments as per 'the clear rules at the time' (to quote you).
If a borrower moves abroad and never again earns UK-taxable income or interacts with the UK financial system, then in practice enforcement basically can't happen.
I would imagine that still applies to US borrowers to a large extent - and to borrowers from the EU country you were born in. Nevertheless, there is still a contractual obligation (aside from a moral obligation) to make repayments if eligible.
You also can’t really blame students for taking opportunities that are offered to them under clear rules at the time.
You can - they are not following the clear rules if they do not notify the Student Loans Company when they relocate overseas - update their new address, provide income details and arrange repayments if eligible.
So, I’m not sure why people think this is some kind of loophole or surprise.
Oh really.