Admittedly, I don’t know how pinball licensing works, but it strikes me a bit as unlogical that having a few more songs increases the cost of the license. Unless it is connected with the per play fees going on ASCAP or GEMA or similar, but even then the fewer the songs in the game, the more often the game will play a given song.
But I would also think that the main goal of the brand would be to ensure that the pinball game does not damage the brand. Ideally it should have an advertising effect. The Beatles is such an enormous business- why would they haggle over how many and which songs?