I mean, it wasn't "a clear case of wage theft" as these weren't wage workers; and in any case it's not like they weren't told ahead of time how much the order would pay.
Do you know that for a fact they were told the total amount including tips, as well as all the details of the job, like items needed and delivery locations ahead of time? Gig apps often withhold info until after a worker accepts, to reduce workers ability to focus on desirable orders. In some jurisdictions Uber drivers don't see the final destination until after they accept a ride.