Well, we know that elites existed in the vast majority of social systems throughout human history. And we only have a small amount of evidence in general, we are studying piles of rocks from about 4000 years ago and trying to draw as many conclusions as possible from the small bits that survived. So the absence of evidence does not necessarily indicate an evidence of absence in this case. If that makes sense.
Harappa and Mohenjo Daro were both part of the same Indus Valley civilization. Although they were possibly fairly independent city states they were part of the same cultural group.
Catalhoyuk is interesting, but dates from a much earlier phase of civilizational development. It predates the Indus valley civilization by a similar span of time as the Indus valley civilization predates us. As you go back further in time, societies inevitably become more egalitarian, because they were less specialized and ultimately less civilized. So Catalhoyuk may have been fairly egalitarian, but it would still be a far less relevant piece of evidence than if a more modern city such Mohenjo Daro was egalitarian.
And of course, this line of thinking naturally leads to the conclusion that even if Mohenjo Daro were what we would like it to have been, it would still be entirely valid to argue that such an egalitarian system wouldn't translate at all to the modern era, given the vast differences in technology and human populations that have unfolded over the intervening millennia.