Climbing coconut trees is kids' stuff here cos the old blokes like me don't do it any more!
I used to do it when I was a kid when we didn't have the dwarf varieties. It is actually very easy if you are relaxed. The ringed trunk helps a lot in getting the grip. For the taller trunks, notches are cut into them to easier climbing. Nowadays, city kids don't know anything about this and their parents wouldn't let them try for the sake of their safety. However, if you go to the kampongs (villages) the kids are still good at it.
For actual harvesting in quantity, people still use the short tailed macaque,
Maccaca nemestris to do it. They are way more efficient than humans.