Well... canoes have been popular somewhat longer than cars. Once emptied, one or two people can usually carry a canoe if necessary. Rowboats are often built too large and heavy to portage.

Rowing does spread the work among more of the body's big muscles, though. You don't need a steersman if you glance ahead often enough and set your course by some feature in view astern. Some of us prefer to row facing forward and standing, at least when in haste or close quarters.