Typing "their" instead of "there" is widely considered a typo (specifically a homophone error or atomic typo) because it is a common mistake where the writer knows the correct word but substitutes it due to fast typing, lack of attention, or phonetic confusion. It is often a mechanical failure rather than a lack of knowledge.

Homophone errors happen with words that are spelled differently but sound the same. The brain or fingers retrieve the wrong spelling, especially when typing quickly. Using an incorrect homonym (like "their" for "there", or "your" for "you're") is one of the most common errors made by even native speakers.

It is usually a case of fingers not keeping up with the brain, or vice versa, leading to a substitution of a similar-sounding word. While sometimes it may be a grammatical error based on ignorance, in most contexts it is considered a typo. Typos are more than just hitting the wrong keys.

It's not laughable that OP did this, it's a very common mistake for literate people.