I know that many top players use Luxilon but I do not see the Luxilon logo on the strings or see these players pictured on the Luxilon website. Why?
A Many top players use Luxilon but do not have a sponsorship contract. The players are now required to not have a 2nd logo on their strings. About 65% of ATP top 250 male players use Luxilon (either in a full stringing or as part of a hybrid) and over 45% of the WTA top 250 woman players do the same. Luxilon is by far the dominant string on tour.