First off, your premise is mistaken:
Since all of Christianity is based on interpretation of the bible,
No it's not. One very large group of Christians - Catholics - does not base their entire religion on the Bible. IF you look at Christianity.SE, there are lots of things being asked that aren't just interpretation of the bible.
Secondly, yes, there are somewhat different standards for some of the non-technical sites.
The boilerplate text for /About includes:
Focus on questions about an actual problem you have faced. Include details about what you have tried and exactly what you are trying to do.
Take, for example, the Science Fiction site... How does any of that standard text really applies to questions about SciFi books and movies?
Like any other SE site, the place you want to look is the list of what's on topic. There you'll see that there are indeed on-topic questions that go beyond just interpreting the bible.
As for your specific question:
How is "Can I believe in evolution and still be a Christian?" a real, constructive, answerable question.
... the answers given are a good overview of the different ways Christians attempt to reconcile Genesis's story of creation with the scientific beliefs about evolution and the age of the universe.