Most of them wouldn't have had formal education, which will make their negotiation skills weak. So there could be a prevailing rate based on poor pricing and general agreement of those rates (both on the supply and demand side). Additionally, this puts them in a different social bracket which is more used to taking orders than making fair demands. This of course is not unique to this particular trade.

However, I don't think the skills were particularly in short supply especially back then (I am from Kerala, which translates to 'land of coconuts'). Ultimately the coconuts did get pulled although the workers weren't paid so well.