Question

why are taller buildings in greater danger of being struck by lightning

Answer 1

taller buildings are nearer to the sky level than the shorter ones. when lightning strikes, the taller buildings, mostly those which have satellite connections fitted or any such metal wiring, are more prone.

Answer 2

Taller buildings are more closer to clouds. The buildings have metallic poles and structures which provides a low resistance path for electric discharge. Hence taller buildings are more prone to lightning.