> In fact I often use the "Thing thing" approach to variable declaration and I think I like it. It's an easy way for me to avoid thinking about taxonomy. But it's not that important. If it wasn't possible I could invent different names.

There's no reason that types and variables need to live in the same namespace. The language can know what it's expecting at a certain point. Putting them in different namespaces, like Lisp does, lets you re-use the same name for types and variables even with matching case, and is more waterproof with regards to clashes than a case convention.

> There simply isn't any good reason not to always use the same case for any variable throughout a project.

I agree, but I also feel that there isn't any good reason to have multiple distinct objects in the same namespace whose names differ only by case. It just seems like a recipe for confusion.

When I'm quickly iterating on something, it's nice being able to be lazy and inconsistent with capitalisation. Standardising that in a codebase is important, but it's more of a job for a linter, I think.