Estimates are difficult for developers and product owners

The unique thing about estimates in software engineering is that if you do it right, projects should be impossible to estimate!

Tasks that are easiest to estimate are tasks that are predictable, and repetitive. If I ask you how long it'll take to add a new database field, and you've added a new database field 100s of times in the past and each time they take 1 day, your estimate for it is going to be very spot-on.

But in the software world, predictable and repetitive tasks are also the kinds of tasks that are most easily automated, which means the time it takes to perform those tasks should asymptotically approach 0.

But if the predictable tasks take 0 time, how long a project takes will be dominated by the novel, unpredictable parts.

That's why software estimates are very hard to do.

I am in a project where we have to give estimates in hours and days.

Needless to say we always underestimate. Or overestimate. Best case we use the underestimated task as buffer for the more complex ones.

And it has been years.

Giving estimations based on complexity would at least give a clear picture.

I honestly don’t know what the PO and TL gains with this absurd obscenity.

Hours is insane. But ultimately time is money and opportunity cost. Software engineering can’t be the only engineering where you ask the engineers how much something will cost or how much time it will take and the answer is “it’s impossible to know”. Even very inaccurate estimates can be helpful for decision making if they are on the right order of magnitude

There's two things here that get overlooked.

First, people asking for estimates know they aren't going to get everything they want, and they are trying to prioritize which features to put on a roadmap based on the effort-to-business-value ratio. High impact with low effort wins over high impact high effort almost every time.

Second, there's a long tail of things that have to be coordinated in meat space as soon as possible after the software launches, but can take weeks or months to coordinate. Therefore, they need a reasonable date to pick- think ad spend, customer training, internal training, compliance paperwork etc.

"It is impossible to know" is only ever acceptable in pure science, and that is only for the outcome of the hypothesis, not the procedure of conducting the experiment.