Gee, why won’t Obama just submit his birth certificate in a court of law?
Because no court has asked him for it.
Because courts don't accept documents they haven't asked for, particularly to make a decision on the outcome of a case they haven't yet accepted as appropriate. I gather that you have no actual comprehension of legal processes. But courts don't want and won't accept documents for determining the validity of a posed question before standing is established, a case is established, and they request them.
Asking Obama to do something that the Court won't accept or use as a determination for anything is nonsensical. It's not a valid counterpoint to anything. It may even be, dare I say it, a non sequitur.
Perhaps you should rewatch “My Cousin Vinny” for that lecture the judge gives Joe Pesci during the arraignment.