[JdeBP]

> But why are classic shells shipped without even the simplest "undo" features?

This question is assuming an untrue premise. There are Windows command interpreters that integrate DEL and RD with the Recycle Bin.

* https://jpsoft.com./help/del.htm#r

* https://jpsoft.com./help/del.htm#k

* https://jpsoft.com./help/rd.htm#r

* https://jpsoft.com./help/rd.htm#k