Mad Max Fury Road. They defeat the tyrant, and get the control of the water valves. Then they open the valves and seemingly keep them open. One problem, how long is the water reservoir gonna last now?
Logan’s Run. The city dwellers are freed from the computer’s iron-fisted rule, and Carrousel. But their city is in ruins, and thinks to the computer providing everything. They don’t know how to live without it. The city dwellers are going to start dying off real fast.
Fury Road isn’t that bad an ending. Water flows, but we don’t know how much of a shortage there is nor if will be that much of a problem. This can also be a political thing for Furiosa to gain the good will of the populace before instituting a better rationing system.
But yeah, the end of Logan’s Run is far worse. You have a people who have lived in an authoritarian society where most things are provided for to being forced to requiring free agency in order to live in a frontier like setting they aren’t used to. Most of the people are going to die.