I'd have to guess that it's a more profitable market. I'd assume far more people are likely to be persuaded to try their hand trading since they can make a million dollars in only a couple weeks with little risk and only $1000 down! A lot of shops have introducing broker or similar programs where you sign-up clients for them and get a cut of the spread for every trade or commission or similar. Has the benefit of not being illegal, and, free money!
Not really sure what you mean. But as far as trading forex, it's relatively cheap and easy (as these things go as regulation in most jurisdictions is either lax, or non-existent) to set up shop and quite lucrative. The majority don't actually settle trades, they just match their book and trade the rest naked. Because, let's face it, it's pretty much guaranteed that almost all retail trades will blow out their accounts. I wouldn't let my money anywhere near those sleazy bucketshops.