If you consider spaces “unusual” I would say you haven’t encountered a single average user in your lifetime. Spaces in file-names is the single most common thing people have, outside programming environments.

As a x-plat developer, the only platform where I (still) regularly encounter these kind of bugs are platforms where solving problems through scripting is common, like Linux, where the primary means of operation is through stringly-typed statements getting parsed and processed in a untyped-fashion. It's not very reliable.

On Windows people more often use “real APIs” (because scripting doesn't really work as well), but then these problems just goes away.

Pros and cons, I guess.