Since it's pretty much on the Equator it makes a lot of sense to keep time like that -- days and nights have the same duration all year long. Such a system doesn't make sense for places that have wide variations between seasons, unless you also alter the length of the hours to match (which I think was done at some point somewhere in Europe, but I can't find any references)
Even on the equator, sunrise and sunset times will vary by +/-15 minutes, because solar days are not of equal length. But yeah, close enough for imprecise use.
