In tennis, a match is over when a player has won two sets (best of three). Why, then, are three tie-break sets to 10 always played in the GotCourts League?

There are several reasons for playing three tie-break sets:  

1. A court booking usually takes an hour. Three tie-break sets to 10 (with decision point at 9:9) practically always fit exactly into one booking hour. Each tie-break lasts about 15 minutes. If a 2:0 tie-break set score were to be stopped, it is highly likely that the booking hour would not be over.  
2. Even with a 2:0 set lead in the tie-breaks, the third tie-break is played. The ranking system makes a difference in the point standings depending on the final score after sets. There are «big» wins/losses and «small» wins/losses. A «big» win is a 3-0 after tie-break sets. A «small» win/loss is a 2:1, 2:0, 1:0 after tie-break sets. Both players can gain valuable points for their ranking by winning the third tie-break. In «big» wins, the winner/loser gets/loses more points than in «small» wins/losses.