some games also don't have the code to select color preference...I think mostly older ones. But this should impact both real time and turn based games equally.
There are some rare cases where color has a direct impact on some aspect of the game, requiring that color preferences are excluded. Off the Rails in your recent history is one of these cases because player colors are actually printed on the board, and this determines turn order.
Another point to consider is that color preferences is not a best fit scenario. Player 1 gets to choose color, followed by player 2, then 3, etc. So even in the same game with the same players, color choices may change depending on player order.