Guys, you're Python 3 unicode experts, already thoroughly familiar with how surrogateescape works. These features are not for you.

The exact implementations don't matter. These need to exist, and they need to be documented with detailed explanations. People don't yet understand what the surrogateescape error handler is, and what it's for, or how to work with it.

People consider surrogate escaping this weird mysterious thing. It's not - it's a really simple mapping of the 128 bytes with the high order bit set to a different part of the Unicode code space. These functions make it obvious.

wsgiref.redecode is a natural consequence of the design of PEP 3333 - it makes sense to offer it there, as a hint that frameworks are likely to need it.

We have a serious, serious, learnability problem around binary data handling in Python 3. It's nowhere near as bad as the learnability problem for text handling in Python 2, but it still needs more scaffolding to help people grow in understanding.