[Jay]

Come to Toronto, Montreal or Mid-Ohio and I'll gladly show you the two layers of fencing I discussed. You can even see it in the background of the Mid-Ohio and Portland photos. I've never been to Road America, Portland or Mexico City I can't really say abotu there(I assume you have been to them). The areas above where you don't see fence are all for marshalls and accredited photographers only. I assure you the public has to stay behind at least one layer, likely two layers of fencing.

Granted circuits such as Mosports don't have as much fence, but they don't have to deal with the crowds or the high speeds, crashes and safety standards in Champ car or F1 in Montreal's case.