1. Other countries don't have pattern daytrading restrictions
2. Other countries probably don't have uptick rules for shorting
3. From my very scant observations, my impression at least, is that other countries don't have as liquid an options market. It would be pointless to say that because options trading is illiquid and unprofitable in other countries, that the US options markets won't be liquid and profitable.
I think US Single Stock Futures have the likelihood of being as much more successful than those in other countries as US options are compared to other countries' options, and for the same reasons (whatever those reasons are).