I have implemented the fix and got it approved in the span of about 3 weeks (and that was over the Christmas!). Doesn't seem that bad to me, given that it's a change that will affect pretty much any Rust user by default.
I noticed a very tiny typo which doesn't affect behaviour I think. https://github.com/rust-lang/cargo/pull/13257/files#r1464506...
Then there is the fact that it required establishing the whole working group
All for a simple fix that positively affects pretty much any Rust user
In the end, changes in Rust can take a very long time (years) sometimes. It's maintained and developed by volunteers, and it has been growing exponentially these past few years, so not everything can move forward as fast as we would like.