Well, various people have pointed to these issues to explain the challenges of e-commerce in the Philippines:
difficulty to reach customers everywhere: remote islands and villages
lack of good infrastructures (roads, airports…)
limited use of financial services and large number of “unbanked” people who are therefore unable to pay online.
However, it would probably be difficult to single out one reason above the others, as it is most probably the additions of these factors that hinder e-commerce in general in the Philippines. Some areas or communities might be impacted by one factor rather than others, depending on their location, habits, connectivity to telecom networks, etc.