I think usually it's not a matter of not "wanting" to give them. It's a matter of not wanting to take a wild guess - which is talked down if it seems too high - and then be asked to finish the work in that time frame.
Time or scope, at least one of these things needs to be flexible, and stay flexible until the work is done.
You’re on the money about time and/or scope needing to be flexible. Estimates improve as you gather more information and complete parts of a project. Providing early feedback that relates to the original estimate is key!
“This is more complex because of X, and will likely add Y time. Do we want to proceed?”
Nothing worse than getting to the end of an original estimate and only then letting a project owner know it’s going to be twice as long.
Wishing upon a star that people are better is a terrible plan.
Wishing is indeed a terrible plan. Teams that treat estimates as commitments are dysfunctional. Estimates are a tool for budgeting in an agile-like world, and need to be refined as progress is made.
- Estimates (I think it will take X long)
- Targets (I would like to have it done by X)
- Soft deadlines (with low consequences for missing)
- Hard deadlines (with high, usually external, consequences for missing)
and that understanding the model and using those words solves quite a bit of confusion around dates. Of course sometimes targets become soft (or even hard) deadlines because humans are messy, but being able to distinguish those things is a step in the right direction.