I wonder if the problem could be helped by turning the "Loading Zones" into "Loading Zones for Commercial Vehicles Only". I am not sure how the loading zones are arranged or signed downtown, but I did notice a comment on Dick Howe's site on this topic last night.

The comment you're talking about mentions couriers. I get that that might be an issue, but in an increasingly residential downtown, people are loading and unloading at home as well.

.