kEiThZ
Superstar
Wikipedia lists 31 commuter rail systems in the United States, of which all major metropolitan areas (e.g. NYC, Chicago, Philadelphia, Boston, SF, LA, DC) have their commuter rail network operated through their own transit agencies. In fact, only 3 routes operated by Amtrak (Capitol Corridor, Keystone Service and Downeaster) appear in that list and especially the classification of the latter is rather debatable...
My statement might have been a bit too broad. I could see a lot of suburban/exurban routes being in VIA's bailiwick. Niagara, Barrie and Kitchener come to mind. Heck, this is sort of what is emerging on the the current VIA corridor at Belleville, Coburg and Kingston. More to the point though, VIA would probably get more contracts from different provinces to run their commuter or exurban services if it were similar empowered.