Each card value has the same probability, but subway riders' distribution is all skewed. A way to make the hands fair that comes to me right away is to take so

Each card value has the same probability, but subway riders' distribution is all skewed. A way to make the hands fair that comes to me right away is to take some unambiguous information about riders (coat color, presence of a hat, etc..) and calculate a hash that you can read as/transform to a hand. This should transform the distribution to uniform, at least to a degree suitable for an occasional play. Though, this will void the strategical part of the game.