Work made for hire is a legal term which implies an employer-employee relationship (see also https://en.wikipedia.org/wiki/Work_made_for_hire)

Commissioned work is usually not work made for hire in the US, and so your quote wouldn't apply, unless it has been very explicitly agreed:

"there must be a written agreement between the parties specifying that the work is a work made for hire by use of the phrase "work for hire" or "work made for hire.""

Note: Wikipedia suggests it is highly unfavourable to the creator to agree to this term, in comparison to a simpler copyright transfer.