Why might a union find that attaining the goal of employing all its members and the goal of maximizing total union wage receipts to be incompatible objectives?

What will be an ideal response?

To ensure that all of its members are employed, a union must be willing to settle for a wage rate sufficiently low to induce employers to hire all those individuals. In contrast, to maximize total union wage receipts, a union must find a way to attain a sufficiently high wage rate (at which the elasticity of the demand for labor equals 1), which typically will not equal the wage rate required to induce employers to hire all union members.