I don't know about the real numbers but I did have a similar experience. I needed somebody to do manual labor (yea, I know, I am lazy) and was having a hard time finding any in a high unemployment country.

I told my friend about how there is no single guy despite the unemployment. His reaction was "oh, really? They are in that coffeeshop just around all day waiting for jobs".

Turns out sitting there all day was their way to advertise. You just talk to the waiter about what you need and if it requires some speciality (painting, plumbing, etc...) and he points you right to the few guys who do it.

I'm not sure if Facebook will help them since my country has a low gdp/hdi but this might be otherwise for the developed and more connected world.