"No, it's less effort than that"

Whenever this estimation question comes up, developers rarely put themselves in the shoes of the business side, and try to understand why there needs to be an estimate, and why shorter is always better than longer. What they do instead, is try to protect their holy land of software development, and exacerbate the differences between engineers and "the others" - sarcasm and cynisism usually shine through at this time, and that's how you end up with unrealistic estimations.

I've been a developer, PO, manager, director, CTO, the whole thing. I'm still shocked by how most (not all, but most) developers are simply too disconnected from the reality that, yes, they do need to provide value, and yes, that value does have a time factor. Lucky are we as developers, that people actually ASK us how long it will take, and give us the opportunity to explain it, push back, and actually defend your estimates. The sad reality (at least from 90% of my career), is that developers are rarely able to actually engage in business-level conversations, and actually express their thoughts/ideas/concerns/proposals, in a way that it drives the conversation forward. In a way that helps PMs and managers actually see the complexities of the work, and engage in healthy cost/benefit discussions.

> developers rarely put themselves in the shoes of the business side

The simplest solution to this is to make them an actual part of your business. Do your lead devs assist business meetings ? do the dev team get the numbers, get a look at the budget, work with you on the roadmap, look at the user research and brainstorm the features with the business and UX people ?

If not, why would you expect them to understand the business ?

The other side of that dev/business separation: as you put it, that creates a holy land of software development, as everyone has their own silo while expecting other specialists to be well versed into their own problematics.

I think many businesses are working dispite extremely siloed roles for their team members, and people tend to think that's an OK way of doing things as money keeps flowing in.