Attendance, leave, payroll and the rules that decide what lands in a payslip.
People and payroll
Attendance data becomes money at the end of the month, which makes every ambiguity a dispute. One rule, applied the same way to everyone, beats a strict rule applied inconsistently.
An employee who cannot understand their payslip does not trust it. The fix is not a better layout - it is recording how each number was calculated, at the time it was calculated.