Another item may be simple sun exposure. Manual workers in any tropical country are much darker-skinned compared to white collar workers. Basically anywhere in

Another item may be simple sun exposure. Manual workers in any tropical country are much darker-skinned compared to white collar workers. Basically anywhere in subtropics its considered posh to look as white as possible, see massive business ie in India with skin whitening. You won't see many self-tanning creams in shops there but tons of whitening ones.