Because they hope that the jobs created will provide enough of a boost to the economy to offset the cost of providing services for the land. Sometimes this is

Because they hope that the jobs created will provide enough of a boost to the economy to offset the cost of providing services for the land. Sometimes this is done in the hopes of encouraging other companies to set up shop in the area. Sometimes the Governor feels like he/she needs to reward a region for past votes or favors. Sometimes soft bribes are the reason.