Surprisingly a head shot isn’t always best to guarantee an instant kill on many animals. Skull thickness, small brains etc.. especially in species which use their head to battle it out for boss of the herd. But regardless of this the shooting of any elephant is deplorable.
Plenty evidence building through studies of trophy hunting to ‘fund’ conservation that it is having a negative effect, as generally the best trophies are also pack, or herd leaders and they are taking out those with the strongest genetics and leaving the weaker or smaller animals to breed. The ways in which man meddles just never ends.