Why does iOS autocorrect some words but not others when using a bluetooth keyboard? I know that official iOS support for bluetooth keyboards is minimal, and that AutoCorrect is theoretically unavailable. (According to Meg St. Claire via the Apple support forums, this is by design). Yet iOS seems able to AutoCorrect some words but not others: it auto-capitalizes phrases like "The Lord," "Supreme Court," and "United States," complete with a drop-down suggestion box that can be dismissed with the [ESC] button. If you type "teh" on the other hand, it just red-underlines it, which can't be accessed via the keyboard; you have to tap it with your finger. 

Things I've checked:


"Shortcuts" section in the settings -- none of the phrases I mentioned are there. 
Not using TextExpander or any similar software. 
The autocorrection appears system-wide -- not limited to any single app.             


Is there any way to explain the idiosyncracy? I'm using an iPad running the latest version of iOS and an Apple Bluetooth keyboard.
The autocorrect built into iOS since the first iPhone release has been a "smart" autocorrect. It is designed so that we can type quickly, trusting that the keyboard will usually get it right. I've found this to be the case, with the need to only occasionally go back after typing a paragraph to make a correction or two.

In contrast to what you said, I've found that typing "teh" does automatically change to "the" if I continue typing, trusting the keyboard to fix it. There are exceptions. Something to be aware of is that if you use the Backspace key, the keyboard will assume you're manually fixing something; as an example, if you type "teh", don't type any other keys after that, then backspace the "h" and type the "h" again, when you continue by pressing the spacebar, it won't autocorrect the word to "the".

The keyboard gets smarter if you train it by canceling its incorrect suggestions.

It isn't perfect. Sometimes I've noticed that it tries to change "the Lord" to "The Lord" in the middle of a sentence, which is not proper grammar. It also sometimes tries to incorrectly change "its" to "it's", and no matter how many times I correct it, the keyboard doesn't seem to learn from these two mistakes.