A hand swipes left to right, and a new iPad comes to life. The features are flawless and smooth, the curves are soft, and the movements are fluid. No, not the Apple device. I’m talking about the hand model caressing its screen in ads for this and similar tech devices and services. Lots of people talk about the booming tech sector creating jobs for developers, engineers, and designers. Fewer talk about jobs created for people who hold all of these touchscreen devices and multi-touch-powered apps in ads: hand models. There might be a reason for that.