Serious answer: For some, they do change semi-often and don't feel compelled to declare stability. In other cases, it's a stable + widely used 0.x package, and bumping it to 1.0 usually implies _some_ kind of breaking change. (I don't know if that _should_ be the case, but I know that if I see a dependency has bumped from 0.x to 1.0 I'm going to be cautious and wait to update it until I have more time).
In general: People usually aren't too concerned about it.
This list's Zig as an entry, despite the Zig project having very clear plans[0] for a 1.0 release. That's not 0ver, it's just the beta stage of semver.
