Because none of those are exactly relevant - all three had plenty of empty space for alternate options, and at the same capital cost. With downtown to Lonsdale via First Narrows on a $3-5 billion budget, you're pretty much limited geographically, logistically and financially to "west via Burrard Station, using preexisting Expo infrastructure."
SLS is long, but also direct. Norgate and Park Royal aren't. And since the SeaBus route is almost as long as Central Broadway, SkyTrain
should be saving commuters roughly
15 minutes/trip, or at least 12 as mentioned; 4-6 is seriously underperforming.
That's an argument for more bus service on the North Shore in general; Cap Mall specifically would be covered by all SkyTrain options, so you'd get off the SeaBus and take the train over.
A 5-10 minute wait is a
bit more obvious than 1-2 minutes.
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