Why is it a bass singer can sing high falsetto than the baritone singer?

the point where a bass switches to falsetto is lower, so a bass usually gets more use out of his falsetto. the voice is a muscle, the more its used, the stronger it gets. baritones and tenors have a larger chest voice, and dont use falsetto nearly as much.

I think it has to do with the length and width of the vocal chords. In general, as you learn to sing to the outer edge of one part of your range, the opposite edge expands as well. So basses, who sing much lower than they speak, have a wider range in their falsetto singing.