Actually, both the Hague Accords, and the Geneva Convention are for use beween signatories. Those who chose not to sign are not required to participate in, or be afforded, the treatments outlined.
Terrorist groups are treated as Brigands, Pirates and Bandits. They aren't covered by these treaties, as they aren't considered a military group, but are law-enforcement problems. The use of hollow-point ammunition against them would not be considered a violation of the Hague Accords. They are also not afforded any protection under the Geneva Convention, for the same reasons. It's pretty obvious that they don't feel any responsibility to it.
The largest problem stems, as usual, from idiots who really have no idea what either treaty actually contains. Then, there are also those who seek to "explain" what the Treaties actually mean for political gain. Much like those who feel that the Second Amendment is actually some sort of State power, they use a skewed view of history, and wording, to attempt to subvert simple statements to their own corrupt purposes.