This may just fall under the "I haven't been paying attention to the other sites" category, but why are some questions highlighed in blue?
This is highlighting questions with tags that are in your favorite tags. If you haven't manually added any favorite tags, the system will detect when you have a certain level of activity in a tag and infer one for you. If you manually add a favorite tag, the system will not infer a tag for you.
You can customize your favorite (and ignored tags) in your profile. You can also customize these settings in the right sidebar of the homepage and the /questions listing.
So, if you would prefer not to have any questions highlighted, you can simply add a nonsense "tag" to your favorites. Perhaps unicorn? (:
Am on my mobile right now so can't do a full check, but does this question on meta.so answer your query?
Generally meta questions which will be generic across the entire SE network will go in there.