State or association policy ?

[Stat-Man]

The MHSAA Official's Guidebook has the following (emphasis mine):

Unless other provisions are made in advance by schools and officials involved, these conditions shall apply:

1. Officials who work alone or with an incomplete crew are entitled to the fee or an equal portion of the fee for which the absent official(s) is/are contracted.

If the contract for the game states that working solo or shorthanded will only net an additional half of the absent official's fee's, it appears that is permissible. Absent such wording, the MHSAA rule would apply.