They do at Leeds, and most of the Premiership and at TFC here in MLS. Check this video out and see just what the top flight teams are able to discover about their players and their opponents.
With a system like this statisticians and sabermetric types could actually answer the questions about which players are the best. One could run correlations between time of possession and goals scored, or crossing percentage and goals, or tackles won and goals prevented.
Plus with video integration with the statistics this would help to enable the coaching staff to convince some of the players about the effectiveness of new techniques, tactics and formations.
After Sounders FC's contract with Scout7 is there any doubt that they will look into a technology like this?
Quite frankly the future of the game is systems like this in stadiums around the world, and not just the money rich leagues. This kind of tool can help to confirm what scouts are seeing. A nice trial balloon would be funding the placement of these in an emerging growth league (maybe a Central American or Caribbean league) and MLS could help develop their players and teams, while scouting them better as well.
An even bigger thought would be to put them in the national stadiums for World Cup Qualifying or events like the Gulf Cup in Oman right now. Real data on real players, that could be reviewed and analyzed. The future is now.