The person excused repeatedly teaches the group who is expected to compensate.

Every repeated exemption is also an assignment. If one person is always excused from the tedious part, the work does not disappear; it moves quietly onto whoever is nearest and least likely to object. Nobody announces this arrangement, and it usually starts with a genuine reason that was true once and then stopped being examined. What began as kindness ends up as a rule about whose time is interruptible.

Look at a group you are part of and ask where the excused work actually lands. Naming it without accusation, and asking whether the original reason still holds, is usually enough to reset the arrangement.