I came to the comments to see what the reaction to her statements about the necessity of the nobility (at the time) was, and was pleasantly surprised that others defended her.
Yes, Democracy (or republic) is better, but it is impossible to have the better things without having the foundation they are built on and fundamentally require. The people are (primarily) uneducated, perhaps it is because the nobility prevent them from obtaining education, or perhaps it is because they are literally too busy trying to produce enough food for their population. At the implied technical time the manga would take place, they absolutely did not have sufficient fertilizer technology; that doesn't mean they didn't have it at all, but that it wasn't sufficient for the population they had. And as for crop rotation, just because a population on Earth had it at an early time in history, doesn't mean every population had it at the same time. Take the native Americans (or First People, if you will), a large portion of their nations continued to be hunter/gather well beyond other populations "advanced" into "medieval" style eras. Because these populations didn't do "settling down for agriculture" they never developed crop rotation, never had a reason to. Yet, the same populations developed other advancements beyond the European settlers. (I won't get into that wall of text here, simply Google "what the natives developed" if you wish to know.)
Further more, and to continue what another person posted about the French revolution, there are numerous examples of "highly advanced" civilizations falling to "less advanced" civilizations due to war or internal strife. What the ancients knew throughout history, but was lost to history, is amazing, bizarre and tragic.
So, yes, a number of civilizations developed technology that Isekai civilizations seem to lack, but plenty more did not develop the same technology or it was less widespread within them.
Finally, yes, the people are taxed. No, just because they are taxed does not require that they are taxed unfairly. For all we know, some of the nobility in this "other world" are reasonable, and only tax their people what they need to to pay the king.
Hell, even with democracy there is inequality (taxation is just one aspect that this is true). So it's neither a Japanese view, nor at all inaccurate for her to say that people are not born equally. Or are you going to say a child born with (any kind of) disabilities, or cancer, or even to a poor family or circumstances, is born equally to one not born to the aforementioned conditions? Because if you are then there are a great number of people who need to have a word with you...
I have more to say, but have already created enough "walls of text" for now.