Well one of them is that there are a lot of poor people who can't afford to pay for education. I'm not too sure but there could be people who also live in remote areas who do not have access to schools. There are people who also prefer to work than to learn. It varies really, but these are just some of the possible reasons.
Philippines consists of more than 7 000 islands and many are remote islands with no electricity, no schools, no hospitals. In these islands, people still live the way they did hundreds of years ago and unaware of what is going on outside their own little world. It´s not until some tourist or alike who´s looking for a peaceful place to stay for a while that an island get recognised.
One of the main reasons of illiteracy in other areas though, in my opinion, is the system. We don´t have the same policy like in Europe where it says "every child has the right to an education". Philippine policy is "those who can afford to pay, has the right to an education, the more you can pay, the better education you get"... It´s the same when it comes to the health care system, "those who have money gets health care, those who haven´t, suffer and die". All based on the old corrupt system which, unfortunately, will never end.
