It’s more complex and messier than you think.
It requires more and different skills than you think.
The problems in it you think are hard are mostly easy.
The problems in it you think are easy are mostly hard.
When you don’t know about an area, typically you don’t have clear ideas about what is easy and what is hard. It happens that you think that something is hard even though it is easy, or at least that you equate the difficulties of things that are in reality very different.
Also when you don’t know how something works, you tend to judge how hard something is based on how big the effect is rather than an understanding of the process, but when you understand the system and how to use it often small changes can have huge effects.