I guess it could be, but the point of the GP was that the jobs and the population were spread out widely even if the population density is similar. Now I could be wrong, but from what I know from the half of my family living in France, transit in Paris for example is mostly pouring into the city where the jobs are. In this case, everything is spread out, so the density itself does not really matter. The problem is the spread.

Even here in montreal, while the metro is pretty good and we are currently building a pretty nice light rail system you still can't really depend on the rail system if your job isn't in montreal itself. The whole transit system is based on feeding the big city, not move people in between smaller cities. (Also, It's a bit tiring then to hear about just how dysfunctional the US is and how good they have it everywhere else when it's just not true. The American self loathing just get repetitive honestly)

I think public transit is amazing for city transit but does not scale very well when there's something else than the usual suburb->city->suburb pattern of movement. You can't really interconnect every single medium-small ish city at a north American scale