Actually, the Home Office / UKVI does require universities sponsoring international students to monitor attendance and engagement, and to report non-attendance. This has prompted many universities to formalise attendance tracking (barcode check-ins, attendance apps etc.), especially for visa-holding students. Whether they actually do it, is another question.
Yes, but it is not till quite recently that this implied formal attendance tracking of student attendance at individual lectures. For example, here is how UCL interpreted the requirements as recently as 2015:
Formal tracking of attendance at lectures is a fairly new thing in British universities (introduced around 2015 when I was teaching at one).