western meaning oriental or American? oriental got censorships USA just some ppl can't draw and or color /shrug some oriental art just plain sucks too but thats just me.
In Japan any form of sexual arts (i.e. hentai) sell like crazy so people actually go to art school and have years of training on the subject matters (possibly not strictly related to adult materials but figure arts nonetheless). It's easy money from your bed room. Sites like DLsite and DMM can easily accept your work if there is some quality to it and you get royalties every time someone buys your work. The western artists, however, don't do their work for profits (at least most I have seen). If they are good at it, they will probably wind up working for some animated companies.