Why is opposite color bishop ending a draw ?

Hi everyone !

I know this is kind of a weird subject and it is very unlikely to happen in a real game but I was wondering : at the end of a game, if white only has a bishop and his king and black has his king and the opposite color bishop, the game is automatically counted as a draw because there is not enough material on the board left. However in that case, there is a theoretical mate position with for example the king of h8, his own bishop on h7 blocking him, the opponent's king of f7 and the other bishop checking. So I was wondering if there is a theoretical win, shouldn't both players agree for a draw or trying to win on time ? But I know it would be very annoying if one doesn't agree to draw but it is already very unlikely to happen so... And if by any chance, someone could mate, it would be unfair to automatically draw don't you think ? Just wanted to raise the question and have a good day

And sale question for double knights vs king : you can not force a mate position, but there is a theoretical mate position. On top of that, if the opponent's is already in a tricky position with his king in the corner, it's is not that he needs to not play absurdly badly as with opposite color bishops, he needs to get every are most of the moves just right to prevent mate. So yeah I'm kind of balanced between "draw should be automatic" and "draw should be agreed" in those cases

It depends on where you're playing.

On Chess.com, insufficient material is always declared to be a draw.

On Lichess, the game does not end until checkmate isn't even theoretically possible. Because of this, both players having only opposite-colored bishops would not stop the game from ending, because a checkmate can happen if one player is an idiot or is literally trying to lose.

In real life (over the board), insufficient material is a draw unless the player with "insufficient" material can prove that there is an unavoidable checkmate. (There are rare endgame situations where forcing a checkmate with a king and a single knight or bishop is actually possible.)

Obviously, OTB is the "correct" way, but it's not exactly easy to program into a website.

I may have misunderstood your comment but I don't think there's a mate position with just a knight or a bishop, the opponent's king always have a safe square. Even with bishop + king vs king + knight blocking his way in the corner, mate is impossible so I am almost sure it is impossible with a minor piece only

That was a bit ambiguous, I'll admit. What I meant to say is that when the other side has only a king, it's not possible. But if there are other pieces and/or pawns on the board, there are rare circumstances where it is possible, and there are even some scenarios where it can be forced.

Like this:

Or, like this:

Oh yeah I get it now thanks for the answer