Fees are charged by the term and often by direct debit, which is a different system from taking payment per class. Pro-rata joiners, sibling discounts and a missed month all need handling without an evening of spreadsheet work.
Registers carry a safeguarding weight. Who was present, who collected a child and which contact details are current is information that has to be right and instantly reachable, not filed in a folder in the office.
Exam entries land as a batch with a deadline. Collecting names, levels and fees in one place turns a fortnight of chasing into an afternoon.
Re-enrolment decides the year. The families who do not renew rarely say why, and a system that flags who has not signed up for next term gives someone the chance to ask while it still matters.