That's very one-dimensional. It's usually easy to tell what the code does, but what's hard is to modify or add functionality to it. And this is because of various levels of abstractions that hide how things are interconnected.
Another thing that comes to mind is the level at which one is familiar with a particular style of code organization & a set of abstractions. For example, Rails devs really have absolutely no problem getting up to speed with any given Rails app, but people who don't practice Ruby/Rails as their primary language/framework often complain how complicated and magical it is.
Poor abstractions. Good abstractions make it easier to change things, by decomposing the code into cohesive pieces with low coupling so that you can swap them out and having to think about the surrounding pieces beyond their interfaces. A good interface is small and logical.
Good abstractions make it easy to change the things that will change. Abstractions always make some changes harder and some easier, but good ones make hard the things you wouldn't change anyway.
