You're ignoring the point. No one is arguing that foot traffic is hampered. The point is that vehicle traffic is necessary to maintain the local economy. This point is independent of population density or scale. This will be a painful experiment for Barcelona and local businesses will be harmed (i.e. fail) as a result. The first sign of this impact will be declining rents in the car-free zone.

"Many residents, however, shared the much-earlier view of a former downtown merchant, that Eugene had sustained more damage from the mall than it would have from a natural disaster." https://en.wikipedia.org/wiki/... Why would Barcelona (or Seattle) be any different?