I see no evidence the user is confused, they said they wished the syntax were similar to TS. Though they're not the same thing, they do have comparable uses, so it makes sense to wish for similar syntax to reduce cognitive overhead.

> Well, we disagree.

Most people here know the set theory definition of unions. It's simply a niche use, compared to the usual CS definition, which is the one used in the original article and now all the comments.

You're swimming upstream with a definition that doesn't reflect what is under discussion, which you decreed as though from on high, complete with the assertion that most people don't understand unions like you do. They do.