If I teleport in a crowd this dense, I have a good chance of teleporting into someone. And that's a lot more literal than bumping "into" someone. [Shun is unfortunately well aware that teleporting inside objects is a possibility if he's not strongly familiar with the locations involved, and he really doesn't want to risk it in a large, moving crowd in a relatively unfamiliar area.]

Even with borderlines, completely clearing the path of that risk would be just about impossible.