Height isn't considered by commissions.
So it makes as much sense to measure height for WEIGHT classes as it does measuring their big toe.
There is no oversight on height. There are no rules about height. There are rules about weight. Weight is controlled with strict oversight by the state. Height is filled in by the fighter or their manager probably on the same form that has your emergency contact on it.
If someone gets caught cheating with their weight (however they would do that, helium balloons up their ass, diuretics or whatever) there are huge penalties. Nobody cares if you wear shoe lifts to the weighins, or if your boot heels are taller than Dana's.
What is the penalty if someone lies about their height? None. Because there is no rule about height. Because there is no controlling authority concerning height. The UFC only gives a shit about height insofar as it concerns the popularity of a fighter, and the fact is, tall people are more popular. Especially in athletics.
They don't waste time measuring the height of fighters. It simply doesn't matter to them except for marketing.