Soapbox time.
Because professional footballers are monumentally stupid, even by the standards of professional athletes. Even though football and basketball players in the US are capable of doing some very stupid things, I would bet that the level of intelligence is much higher than the average soccer player. Soccer players don't go to college and there are no minimum educational standards imposed upon them when they're young. A lot of them are overpaid, overprivileged scum who have been set on a pedestal all their lives and led to believe that they're something special because of their ability to kick a ball well. It simply doesn't cross their mind that behaviour like this is in any way inappropriate, and recording it for their own edification and amusement and that of their mates is an entirely normal thing to do.