> So if this sort of "insider trading" is bad, what does this mean for other sorts off strategies hedge funds do to get an edge, like flying helicopters to look at how full oil storage tanks are?

This is allowed because you've gotten that extra information through your own methods that in theory anyone else can get access to. The problem here is they're using information that nobody else could possibly have access to, therefore its "insider" trading and it's been illegal for a long time.