Some people have been programed from a small infant that same sex unions are bad and that they must never be gay(sad but true) and so it would be against their conscience to make them a cake, why force the issue upon such people when you can get a cake at plenty of other places.
Every business has the right to refuse services to anyone they choose. No court is going to force service for such a ridiculous thing as baking a cake it's no life and death matter a little insulting yes but why make a mountain out a mole hill.