Why are electric poles given hollow structure?

An electric dipole is placed inside a hollow sphere at its centre. Then

Assertion. A metallic shield in the form of a hollow shell, can be built to block an electric field. Reason. In a hollow spherical shell, the electric field inside is not zero at every point.

Why are coils of electric toasters and electric irons made of an alloy rather than that of a pure metal?

Why is electrical power required at all when the elevator is descending? Why should there be a limit on the number of passengers in this case?