When you start the game, you have no way of telling where any mines might be, so it could be considered unfair if you hit a mine on your first click; however, some people might say that letting the first square clicked never be a mine is cheating. Therefore, this program has an option to turn that off.
Also, you can't know for sure where any mine is until you've uncovered more than one mine; the only way to safely do this is if you've uncovered a square that has no mines around it. Therefore, this program also has an option to make the first square you click have no mines around it.