The work of such charities often seems more concrete. You can see it. Your neighbors or your community as a whole may be directly benefiting from their work. It may be easier to learn about the work of local charities because it is highlighted in a local newspaper, or someone you know may work with the group. You can work with the group and develop the kind of insight that only comes with close involvement.
Nothing can substitute for direct involvement with a charitable group.
But keep in mind that some problems that charities confront aren't easy to tackle at the local level. Take the problem of air pollution for example. Often, some of the air pollution experienced in one area is at least partly generated in another area and carried by prevailing winds. Or water problems are caused by pollution from upstream. To deal with problems such as these may require a regional or national approach.