You're right, but its the standard that everyone has converged on. The assumption is that it is for lithium ion chemistry which is nominally 3.7v
I don't know if this is going to frustrate you more, but I recently needed a small battery so I picked up this unit[0] at walmart, where it came rated in mAh for both 3.7v and 5v. The battery itself also has WH marked on it. A step in... a direction I guess
This is an "82Wh Phone", assuming they're using a standard lithium ion battery in a normal configuration, which is a lot of assumption.
Watt hour is an actual unit of energy.
22 thousand thousandths of an amp hour is a ridiculous use of units, and it doesn't actually tell you how much energy the battery holds.
[0]: https://news.ycombinator.com/item?id=33891055