Why do you classify that as a dark pattern? It's not harming people in any way, but the opposite.
It's lying. Lying is inherently harmful. Just because a computer is doing it doesn't make it unethical. Especially since people trust computers to be precise and correct.
By the way, people do really not expect progress bars to be correct. They may with they were, but not expect.
5 minutes left, 4 minutes, 23 days, 1 minute, 4000 years left.
The last 1% Taking longer the first 99%
If you installed the same software repeatedly get an idea of how long each section of the bar would take.
Windows 3.1 I’m looking at you.
Page 311 of the .NET Framework Design Guidelines has this quote from Chris Sells (then a program manager for .NET, I think):
> Please make progress reporting move forward, if for no other reason than my family makes fun of me when they see a progress report going backwards, as if it's my fault. Personally, I've implemented several progress percentage algorithms and while I often can't get the timing to be smooth through all stages of an operation, at least they always move forward. In fact, I think you'd have to work extra hard to make them move backwards.
Please explain how lying to your users is good for them.