I love the way YACReader Library looks:

i.imgur.com/voowu2b.png

But why do some folders look like this? And is there a way to get it to look like the above flow view?

i.imgur.com/o6gEl1r.png

Time ago folders didn't have their own view, so you could only visualize the comics in a folder. Now, when a folder doesn't have any comics but it has subfolder a view showing those folders is shown. The only view that supports that content is the grid view. The plan is to support mixed content in the future.

The button in the top bar to change the type of view (flow, grid, info) only works for the comics view.