Bishop plus rook pawn sometimes cannot win! The h-pawn promotes on h8. h8 is a dark square but White's bishop moves on light squares. If the black king reaches the h8 corner, nothing can drive it out.
Black to move. Run to the corner with the black king and save the draw.
With a dark-squared bishop White would control h8 and win. Look at this detail before entering an endgame: rook pawn plus the wrong bishop means half a point despite the extra material.