Because the competition is a complete joke. Three of the teams come from countries without team competitions, whilst Togliatti signed-up a load of ringers for their challenge (Sullivan, Holta and Crump), none of whom compete for them in the Russian League.
I agree that the competition is not a bad idea in principle, but you'll always have the problem of the same riders competing for different teams in different countries. The only way around it is for teams to sign-up separate squads to their normal league competition, and then have enough meetings to make it worth their while. Of course, it won't be much of a 'Champions' Cup if champion teams are not able to track all their usual riders!