Attendance is a signal before it is a rule
Absence usually means something specific.
Attendance requirements exist and must be administered, and treating attendance solely as a compliance matter loses its diagnostic value. A student who was reliable and has begun missing mornings is telling you something, and the something is usually work, money, health or a situation at home.
A conversation at the second absence resolves a great deal that a warning letter at the fifth cannot. It also frequently identifies problems the school can actually help with, particularly around timetable conflicts with work.
The undisclosed factor in many cases is employment. Students working more hours than they should, for financial reasons, will not volunteer it because of the consequences, and a school that responds punitively guarantees it stays hidden until it becomes a bigger problem.
None of this displaces the obligation to monitor and report where required. It concerns what happens in the space before those thresholds, which is where the outcome is actually determined.
It is worth adding that the first fortnight is also when most withdrawal decisions are made, frequently for reasons unrelated to teaching: accommodation that turned out to be unsuitable, money running short, or a family situation. A conversation in the first week catches several of these while something can still be done.