Dude. Half of us are neurodivergent... which means at least half of us will think this is deadly serious, even if it isn't.
Fair.
As far as the original poster goes, as a long-time player of 3e D&D I don't think that there is necessarily any simple answer to the question. Do spellcasters want to rule? Are spellcasters common? How high of a level of power do people commonly reach?
In some places in my world, there are governments of spellcasters. In other places for different reasons there are not. Not everyone agrees with the idea "The most powerful should rule." There are other sources of authority than might.
Now as far as high social status goes, yes that is very much true. A wizard or cleric is always addressed as a quasi-noble, and both do have significant social and legal rights - for example, neither is subject to most taxation and both have rights of privacy and curtesy regarding their persons and possessions that wouldn't be extended to ordinary people. A wizard is addressed as "Your Potency", and after that "Sir" with a verbal rank then equivalent to a baronet or mayor. On the other hand, a wizard believed to be misusing their power is subject to charges of witchcraft and being lynched or summarily executed if the legal authorities are inclined to believe the charges.
One thing that is absolutely true is that religion is vastly more important in setting than in a typical game. In a typical D&D setting religion parallels modern reality, as a thing that is set off to the side and becomes an optional part of life that you can choose to engage with our not. It's not nearly as tangled up in life as it was in say pagan Rome or medieval Europe or pretty much any time before the 20th century in India. In reality, with a host of very interventionist gods with active miracle performing clergy, we'd expect it to be an order of magnitude more intertwined in life than in any real-world example. The pagan Romans who intertwined divination into every aspect of government, thought the neighboring Etruscans were a bit superstitious and overly religious. The average city in my world is more religious than the Etruscans. Everyone is a member of two or three mystery cults at the least. The alphabet soup of modern government agencies are in game world just cults with official roles in civic life. The homeless shelter, the orphanage, the school, the graveyard, the bathhouse, the gymnasium, the courthouse and possibly the brothel are all very likely just parts of temples and run by clergy of a particular deity. Your butcher is likely to be running out of the back of a temple. The police force is also a cult. Every single aspect of life is supervised by and intertwined with worship and ritual. Growing large enough to support more temples and more full-time priests is a major goal of every municipality, because there are obvious transactional benefits to having that daily blessing of a particular deity to say nothing of the general favor of that deity over an aspect of life - or at least not having their displeasure.
I've never found the classes so imbalanced that an ECL adjustment would be necessary or effective. To the extent that there are balance problems, you can tweak the rules in more subtle fashions than that. Certainly, I don't find there to be any real balance gaps in the version of D&D I play (or in any prior version say 1e/2e) before 13th level or so, a height of play I rarely do and which represents NPCS that are nearly as uncommon in my setting. But the last campaign I ran, a single 18th level wizard - the sort of thing that might come around every few centuries in a particular region - was basically governing the politics of an entire region just by his personal power and influence. So yeah, high level casters are super powerful and society recognizes that.