I imagine the reason is as stated above, that grasshoppers/locusts are hard to get in the US, unless you catch them yourself. I was recently at the Smithsonian and they had an exhibit on insects, arachnids and other creepy crawlies ( live bugs and many to handle ). They had lubber locusts which the woman told me are native to Florida and can't survive a northern winter. I wonder if it would be possible to get those up here and try and breed them as feeders. The adults were large and spiny but they would probably be good for large herps and the young would probably make good feeders for chameleons.