Why were egypt and south africa important colonies for britain during the "scramble for africa"?

Works produced by lost generation authors often shared which theme

Me a slaveowner who worked a slave to death or be a slave to death, a. cannot be tried for murder in criminal court but could be sued for wrongful death in the civil court b. cannot be tried in court because there was no law against the mistreatment of slaves. c. could have his form or plantation confiscated by the state and sold to the highest bidder. d. could be tried for murder in most southern states.

Why would employers want there to be large numbers of unemployed workers around?