Because when the US buys the token for 5….
When it gets to soviet territory it can be cashed in for 10.
Thats to make it worthwhile for the allies to do.
Now I see better.
It is worthwhile for Allies to give IPCs to Russia, to get some troops in Europe it requires a long logistic line.
Simply giving (up to 12 IPCs) to Russia will allow a moving of 4 Inf from USA to Russia almost instantly.
When Russia and Archangel are part of a decisive ETO, it is in itself an incentive… unless playing with a greedy and selfish USA player.
That’s why it required some limits and the possibility to destroy some of this IPCs for Axis.