That example isn't comparable to the kind of contracts that were originally being discussed. A contract with fixed hours on the scale of months doesn't have the same degree of stress as one with hours varying from day to day, week to week.
Fixed term contracts are allowable, because taking that thinking to the extreme would mean never being able to terminate a worker, even in cases where their employment becomes obsolete.
The issue revolves around "technically being employed" - having a contract which doesn't entail consistent or sufficient hours, and then not even having the choice to work enough to get by. This unfairly pumps employment figures for companies and the government, who can say that they have X workers, while denying an honest representation of how much people are actually able to work.
My original question was - is there an example of a job which could justify these kinds of fluctuations in working hours and subsequent income?