The real reason is Botswana is getting more tougher on its migrant laws, the old days of a freindly nation looking for for expats are over, compared to the rest of Africa it is still friendly, but you gotta make yourself look good, I guess...the government has invested in pilots, enginers etc..So the job is advertised if a local can take it (or it is a legal requirement)...but yes they will need outside pilots for some time to come.