Oh, whoops, was actually referring specifically to the Locust tree. Not sure your issue with Tulip Tree. It's range includes Toronto, and it won't be a "street tree" rather a park tree. And what would a good similar alternative be to Scots Pine, would it be Jack Pine or Red Pine? Cuz Jack Pine wouldn't be native either.
If you wanted a conifer that would grow Lakeside in southern Ontario, you would choose between White Pine and Eastern White Cedar.
White Pine is a good choice in that it will give you a 60-70ft tree if you give it the right conditions and would be excellent for nesting birds-of-prey.
It also has a fairly slim profile.
Red Pine naturally grows in sandy soils and on cliff tops. You can make it work, if you put the right soil mix in, but in full sun, its gonna be a fat tree at ground level.
Red Cedar is also native, but its what most people think of as Juniper (the vertical version), it tends to like crappier soils w/low competition.
White Spruce is acceptable as a next-to-pavement conifer, because its salt tolerant. But this is really beyond the southern end of its range which is really the Oak Ridges Moraine, and with climate change it's expected to struggle in Toronto.
****
Tulip tree is ok. The very northern limit of its natural occurrence (where it will regenerate) is about Hamilton area, and that barely so.
Everywhere I've seen the City try it as a street tree it dies.
It's highly viable if you give it enough good soil, no salt, preferably not too much wind, and it will look gorgeous.
In so far as the planting spec accommodates this, I can live w/Tulip Tree.
Having seen some very suspect choices by landscape architects in terms of where and how species are sited in their designs, I worry about fussier species choices.
