Just this week I had a lengthy 2 day discussion involving 4 other employees, 8+ long emails, and hundreds of words in chat ... all to figure out that we need to add an if/else statement and two simple lines of code.
The code took 2 minutes. The discovery took 2 days.
The "curse of knowledge" works both ways.
Of course it's not the code itself that is complicated, but what do you want the overall system behavior to be (are there upstream/downstream/breaking effects?) and why. And do you understand the system well enough to know the right way to make the change - sure it only took you 2 minutes to code it but that's because you already understood the system well enough to know the right place to change the behavior.