You need to edit at least a certain number of characters (might be 6). So if you want to correct a = into a ==
you can't. Well, you can... you have to make a few other bogus changes. This bugs me.
And then there is the other problem where edit reviewers have no clue of what they are rejecting and instead alienating the person who suggested the edit (rightfully). But that's a completely different point, admittedly.
Still, I don't think less-than-six-character edits would be a particular problem to handle as the edit review queue is often enough empty or very short.
But agreed, some limitations are a bit stupid and annoying at times. E.g. you downvote an answer based on the belief that it is wrong, further discussion reveals that it is in fact correct, but since more than five minutes have passed you cannot remove the downvote or turn it into an upvote unless the question is edited again. Which leaves to bogus edits just for being able to change a vote again.
Or award the badge only for substantial edits while still allowing fixing typos (and sometimes in code a single-character diff can make a huge difference).