This introduces a distinction between new and old shopping malls that is irrelevant to the discrepancy at hand. The author refers to new shopping malls, and does not reference economic effects at different stages of a mall’s life cycle.

This widens the discrepancy by implying the mall's economic activity should be mostly reflected in the community’s overall economy. If most customers come from out of town, they bring economic activity to the community that would otherwise go elsewhere.

This implies the mall causes an increase in the community’s population, which if anything would boost the larger economy even more than expected. If the mall draws workers, then those workers will spend their money in the greater community and increase the total economic output.

This explains why a new mall will contribute little to the overall economy. If the mall draws business from other places in the community, it causes a redistribution of existing economic activity but does not necessarily generate new activity.

This is an irrelevant distinction between the economy when the mall is being built and the economy after the mall is built. The mall offering low-paying permanent jobs does not explain its failure to grow the community's economy as a whole.