...Extend the 404 to Casino Rama? Reminds me of the South Park Episode where the native casino operators want to demolish the town to build a freeway to their casino.
I assume Highway 7's traffic volumes are 'lower' than expected because drivers just don't want to deal with it. There are alternate routes like the 401. Volumes will go up a lot whenever the freeway is built (cough cough induced demand)
Highway 6 on the other hand- that's high because there's really no other alternative. Unless you want to travel through Cambridge on Highway 24 instead, get to Brantford and then backtrack on the 403, Highway 6 is just more direct.
Highway 12 through Orillia does seem simple to widen, but I guess it's still operating semi-decently since there's not many intersections and fronting business. It does get really congested during the summer however.
Highway 10 does need 4 laning all the way up to Shelbourne.