> Saying "Humans suck at estimating" is nonsense. It's a skill that can easily be improved - usually at the cost of some up front planning - and there are plenty of resources to help you with that.

This is completely dependent on what you're doing. If you're implementing yet another CRUD app, then sure, you should be able to estimate that to within 10%. If you're developing something a little less predictable, like a game or something for R&D, then estimates go right out the window.