They probably want to limit the time that they have their legs cramped up - especially after a game.
They want to ensure that the players get as much sleep at home to maximise performance and ensure that any training the day after a game can start when the coaches/fitness people want it to start, and not because they had a long bus ride home.
Even in a moneyed industry like football, I can't believe that the clubs would spend so much money if they didn't have some specific benefit for it. Even if it were only to appease the players (increase their time at home etc), this might be enough to get a better performance from them and eventually bring more money in through wins/final league position.