'The population want employment' should be accepted along with 'The population wants employment'. The population is singular as its a collective noun- the population is one thing . (It can also be seen, however as a group of people and therefore plural (wants))
Generally in AmE, collective nouns take singular verbs. (There are exceptions like "police" that require a plural verb: The police want to talk to you.)
British English allows both plural and singular verbs for collective nouns. It is one of the more obvious differences between the two varients.