Based solely on the fact that Peach is a princess, we can conclude that the Mushroom Kingdom is a monarchy. While that's all well and good, when you take a look at the Mushroom Kingdom as a whole, things start to seem a little bit fishy.
The world of Mario is a rich ecosystem of turtles, other slightly different turtles, mushroom men, and big headed creatures named for ethnic slurs. However, while there's no shortage of indigenous species in the Mushroom Kingdom, there is a marked shortage of one thing: humans.
In the entire series, there are a total of six humans: Mario, Luigi, Wario, Waluigi, Daisy, and of course, Peach. Furthermore, of these six people, four of them speak with thick Italian accents, and while I was never all that great at geography, I'm fairly certain Italy is not located in the Super Mario Universe.
All this suggests that humans are not native to the Mushroom Kingdom, and raises the very important question: How did Peach, a human, become the ruler? Either she married her way in, which is not likely, given that she's still single, or there's a much more sinister explanation: She's the leader of an invading force that seized power by means hostile military action.
While we're on the topic, does anyone else think it's strange that, of the six humans, the two pretty white girls are princesses while the four people of Italian descent are all laborers?
A lot of you are probably saying "Hey, lots of people aren't royalty. That doesn't mean anything sinister's going on!" But here's the thing: what about Mario? He has literally saved the kingdom from destruction countless times. That, plus, his strong ties to the monarchy should mean that Mario should at least be a duke by now. Why the hell is he still a plumber?
Below Italian in the horrifying hierarchy of the Mushroom Kingdom are the Yoshis and the Toads. Together, these two species make up the servant class, as shown by Yoshi continually helping Mario along on his adventure, and Toad serving as Peach's attendant. While the existence of a designated servant class is fucked up enough already, the fucked-uppedness is compounded by the fact that Peach and Mario are total assholes about it.
Who Mario calls Yoshi is a member of the Yoshi species, and who Peach calls Toad, is a Toad. Those clearly aren't their names. Calling a Toad "Toad", is equivalent to calling someone who works for you "boy" or some shit, which makes you a total asshole. Peach has clearly just created a kingdom in which it's acceptable to treat certain classes of people with total disregard. Still don't believe me? Answer me this then: If Peach had even the slightest iota of respect for Toad, do you really think she'd be so willing to use him as a human shield in Super Smash Bros?
Some may say "Hey! Peach can't be the villain of the Mario franchise because most of the games are based around saving her!" Well to those people I say "Shut up you impatient assholes! I'm getting to that now!"
One of the most puzzling aspects of the Mario series is that the protagonist doesn't appear to have any special powers that would qualify him to be the princess's continual savior. This is made doubly puzzling by the fact that someone else in the Mushroom Kingdom has proven time and time again to have super powers. That person? Peach herself.
In the Nintendo DS game, Super Princess Peach, is shown to be able to turn her emotions into different super powers which, though exceedingly sexist, means she is much more capable of defending herself from Bowser than an fat, acrobatic plumber. Why doesn't Peach PMS herself into becoming the Human Torch (an actual power demonstrated in Super Princess Peach... sexist bullshit...) and save herself?
There are two possible explanations for Peach's passivity: either she's lazy, or, much more likely, she likes to be saved. Actually, I would go so far as to argue that more than just not saving herself, Peach actually orchestrates all of Mario's adventures just because she gets off on being rescued. I mean think about it, when you beat a level in Super Mario Bros, what do you find? It's Peach's servant Toad standing in an empty room telling you "Thank you Mario! But our Princess is in another castle." If Peach was really kidnapped by Bowser, do you really think he'd let her servant stay behind and give people clues on how to rescue her? No. Bowser would maul him.
Peach has clearly spent a lot of the Mushroom Kingdom's money on building extravagantly booby-trapped castle, sending Mario on a bunch of crazy adventures and risking his life, just because she likes playing the damsel in distress. She's basically just Jigsaw from the Saw movies, but more self centered.
Actually, while we're on the subject...
In Super Mario 64 we get to take a peek at the castle Peach calls home. As you might expect it's pretty swanky, complete with a hidden slide, a bunch of magical artwork, and a stained glass portrait of Peach herself right up front. For as nice as the castle is, though, there are a couple of things that spark some red flags.
The first suspicious aspect of the castle is the basement, which Peach keeps locked. When you finally gain access to the basement you find that it's not as ornate as the rest of the house: It's gray, full of stagnant water, and the only piece of artwork is of a horrifying fire-beast. You know, actually, come to think of it, it kind of looks like... HOLY SHIT PEACH HAS A DUNGEON!!!!
If that weren't horrify enough, directly connected to the dungeon is the backyard which is nothing but a fountain, some bushes and a whole lot of dirt. Oh yeah, and there's ghosts. Lots and lots of ghosts. In fact, the first time you back there, you are lead there by one of the Boos in a manner that almost seems like it's trying to show Mario something... a body perhaps?
Granted, this is all speculation as I haven't been able to acquire a search warrant yet, but tell me this: If you knew someone had a secret basement dungeon and backyard full of restless spirits, would you still think she was worth rescuing? Yeah, didn't think so.