I don't think every time someone volunteers with children that they are pedophiles. I mean, there are so, so many youth organizations that depend on good adults to volunteer or they wouldn't exist. I also don't think it's completely unusual for a team/club sport to have a physician that comes in on a regular basis to see athletes for free. It's pretty common around here, actually, for lots of different sports. Although, it's usually a physician who either did that sport (i.e., a doctor who sees gymnasts actually was a gymnast when he was younger) or has a child on the team.
That said, I do think if you want to target children who spend time away from their parents, that's probably a good way to start.
I don't know what the answers are, except to limit the opportunities for abuse.
In other words, an adult shouldn't ever be alone with a child, etc.