There's a two hour edit window to allow people to do any editing they need to, but Chowhound is a conversation, and posts get direct replies, the meaning of which could be changed by future editing. Imagine a post that says "The Local is awesome! I love the burgers, especially the one with blue cheese." and a reply that says "I totally agree with you -- especially about the blue cheese." A year later, the first poster has a bad experience at The Local and feels that they aren't giving enough blue cheese on their now famous blue cheese burger, so he edits his original post to "The Local is so overrated. They completely skimp out on the blue cheese on their blue cheese burger. It used to be sooooo much better." And now the first person's reply is still there, but the meaning is completely the opposite of what was intended when they posted it.
If a typo is something important, that would change the meaning of your post or make it hard to understand, or even if it's just bugging you tremendously, you can hit 'report' and ask the moderators to make the changes. If there are more than 1 or 2, you can also send a revised copy to us at email@example.com and we can replace it for you.