If you’re close to a problem or a system it can be easy for you to add things to a system or simply dismiss options out of hand. You know what the implications of what you’re doing because you’ve been staring at the system for ages.
Someone else, who happens to get shoved into the fray, doesn’t have the context that you have. The things that are stupidly simple can be stupidly hard because ever step must be carefully mapped and considered before moving ahead.
Sure the careful mapping and consideration are the hard-earned way of getting to the same context as the old pro, but it’s a frustrating exercise for both sides of the equation. The experienced person is wondering how can the idiot be so stupid; the new person is getting lost in the weeds because their filter isn’t yet ignoring all the things that aren’t important.
That gets into the next thing — one of the things that you get with experience is knowing what to look for. Not knowing what you should be looking for leads to everything being given the same level of importance. It’s not high or low, just the same. Which is the problem.