Admit it. You get it wrong sometimes. I don’t care how many degrees you have, how steeped you are in the highest register of formal discourse, how vicious you are with the red pen, how many children’s wrists you have slapped with a ruler. You sometimes write there when you mean their or they’re.
Yes, you. You may catch it every time, correct it before pressing “send,” but you do it. The language just makes it so easy to do. Not only are these three words pronounced exactly the same, they are all constantly in use in everyday discourse. Wait and weight or flour and flowerjust aren’t as frequent. Most people aren’t going to mix those up. So there’s no reason to be especially proud of not mixing them up, or to make smug memes about them. But there/their/they’re is a cleverly laid, dastardly trap. To tout your mastery of this trio is an act of pride in your ability to skip over the trap.
So who set this trap? We did, of course, which is to say all the English speakers who came before us. First, in the earliest stages of Old English, we had the word for “there,” which was then spelled þǽr (thǽr). The word for “their” was hiera, so there was no problem telling them apart. But when Scandinavian settlers starting coming over around the year 1000, we started borrowing a few things from them, including their word for “their”: þaire (thaire).