The gaps aren't that bad, personally I like the gaps as small as possible but some are ok with gaps.
Most of the time it's just a case of fine tuning, you can see in some of the photos just where the ears are touching in one spot. Also a lot cut a step into the top of the ear as it sits over the join better, the back overlaps the front and leaves a small gap with ear on top. Most of your issue is you see the back top of your ear is touching and the front isn't, to fix this you need to trim a step. Here is a great thread, sadly it is missing some photos but it will give you the idea.