It is possible that a project is non-trivial to you but trivial to someone else, then that someone else could properly estimate it. Also most software projects

It is possible that a project is non-trivial to you but trivial to someone else, then that someone else could properly estimate it. Also most software projects are trivial so I don't see why estimations would be impossible, it is not like your typical react app is going to push boundaries on research topics. They might push boundaries to mediocre developers though, in which case it is a non-trivial project for them. I think the real reason estimations are hard is that basically every developer is working on projects too hard for them. Like, if you are so good at your current job that you can reliably churn out good solutions with ease then instead of just producing you would move on to do harder things for better pay.