Jon: "[didn't] change anything, except to take an inordinate amount of time." Yeah, most people only use that item once... unless their memory fades a bit.

It could be that we don't always see an immediate delete/change because that task is assigned a low priority. If the computer/app is busy at something else, that task just has to wait a bit.
As for the "Delete" changing to "Un...", that was a UI groups call:
1 Lie to the user. It's not nice to fool folks into thinking things are happening faster that they actually are. Maybe show a progress bar? (Marketing prolly won't like that!)
2 Wait for task completion and make things look like the computer/app is not working or slow? I thought that's what the spinning pizza was for.

Of course there is a teeny, tiny possibility that there is some kynd uv erer in the coad.
