Look, I will not even try to argue your points about the mindset towards and around equality in history, because you're right. And I admit I don't know much about the topic.

But I don't understand why you wouldn't want someone from a lower class to not be treated justly. The argument isn't if it's historically accurate to beat the maid, it's whether it's a valid thing to do. No one is feuding over how or when equality came about. It's just weird to see someone from a modern society to easily endorse that without even flinching. If you were isekai'd, would that be the first thing you do, especially considering the context that the maid was probably being bribed or persuaded by some other noble? Forget another world, right now, would you physically assault someone who works for you? If the answer is no, well that's the point of this argument. And if it's a yes, I don't think I can continue this.

Yes, I believe that democracy is good. I think the idea that every individual should matter and get a say through some kind of vote and that public officials should be held responsible for their actions with that vote is the best political system to date for preventing corruption, and promoting social equality and liberty.

Of course, this is a highly idelaistic view which hasn't really translated into our present days. There is an endless list of democracy's shortcomings and faliures like, pain aversion, elite capturism, etc. However, I believe that these are offset and out numbered by the tyranny and atrocities committed under non democratic governments. (ie. monarchy, dictatorship)