??? What other options are there? Rent a car and abandon it in Horseshoe Bay? Take Canada Line then "Blue Bus" with a 5.5 month old and all the assorted luggage after a nearly four hour plane ride?

Taxi seems like the sensible choice to me. They will be able to drop their luggage in the cab trunk, then again right in the Horseshoe Bay BC Ferries luggage drop.

When you're travelling with a baby you pay for convenience, and a taxi is convenient.