shouldnt 100% of the lcs pass go to the teams?

1. Riot is not a trillion dollar company. Not by a long shot. A few billion, yes.
2. Revenue share for this sort of thing is fairly standard. The NBA and NFL, for example, average out to about 45-47% of merchandise sales going to players, if I recall correctly.

I doubt you can find any business anywhere that gives one hundred percent of the proceeds of anything for licensing, if they did, they would be hemorrhaging money.