Because cars aren't crows?

By car, Google Maps says "Poplar, Blackwall & District Rowing Club" to "Greenwich Pier" ( https://www.google.com/maps/dir/Poplar,+Blackwall+%26+Distri... ) takes 6.9 miles and 22 minutes.

Using the Greenwich Foot Tunnel under the Thames, it takes 7 minutes to walk the 0.3 miles.