A "partial solution" used in my area is designated "Loading Zones" in commercial business areas. Each zone is generally a space about the size where 2 to 3 passenger cars could parallel park, and sits empty most of the time. The "waste of spaces" rouses the ire of those looking for a place to park their passenger car; but the space can only be legally used by vehicles with a "commercial registration" and typically has a 15 or 20 minute time limitation posted.

In some places, a non-commercial driver is allowed to use a Loading Zone to drop off or pick up passengers, but usually at least the driver must "remain with the vehicle," and in some places technically must move on if requested. In other places this usage is restricted to places marked as a "Passenger Loading Zone."

While the police here will place a citation on an "illegal" user's vehicle, the adjacent business, with proper posting of warnings, can call a commercial towing business to have illegals towed and impounded. This has some effect, but the business operators' passion for "not affending anyone" often results in "offending almost everyone" by their tolerance for improper blocking of the spaces.

The problem remains that some local delivery trucks are too large to get in and out of the designated zones, so they still "park" in the traffic lanes for deliveries and pickups; and this remains a legal activity. Since it's a "judgment call" on the part of the driver, it's difficult to enforce failure to get (completely) out of a traffic lane, even when there is an adjacent Loading Zone.

I will note that in areas in "younger" US cities there are few two-lane streets in commercial areas, so although a delivey van may impede traffic flow, it's unusual to find a place where one blocks traffic. There is nearly always room for drivers to "filter through" in the remaining lanes. (This isn't a rule, just an observation.)

John