This has a lot to do with the fact that Apple doesn't have to worry about two types of touchscreen input (thumb and stylus), they have no contextual menu tap'n'hold to worry about, and that there's no text-selection process to worry about (that, and they don't have to deal with the N800's noisy touchscreen and its weird input drivers). The issue is more complicated than you think, and has its roots in system-level stuff that MicroB (well, the browser UI) really doesn't have much control over.