A register does not charge a subscription, which is why it always looks like the cheaper option on a comparison sheet. The costs it does carry simply never appear on that sheet: repeated data entry, delayed reports, handwriting that has to be interpreted, records that go missing, and hours spent reconciling the same information across departments.
Consider what happens when a principal asks for current fee arrears. In a manual setup, somebody opens the fee register, tallies by hand or transcribes into a spreadsheet, cross-checks against receipt books, and chases the branch or class teachers for anything unclear. The number arrives a day or two later and reflects the position as of whenever the tallying started.
None of that work produced anything new. It was pure reconstruction of information the institution already possessed but could not read. Repeat that across attendance summaries, admission status, exam progress and staff records, and the labour is significant — and it recurs every term, forever.