Please explain how a handful of delivery vehicles moving through a neighborhood each day for deliveries is more traffic than every single homeowner having 2-3 cars all of which are in circulation on those same residential roads each day.

The trucks are not a replacement for ordinary traffic.  They are in addition to ordinary traffic.  

Moreover, residential streets were not designed for trucks.  They are designed for cars.  The turns are often so tight trucks can't make them without crossing over into the wrong lane or climbing the curb.  The asphalt and subbase are thinner, and don't bear up under the load as well.  A parked truck on a residential street can bring traffic to standstill; a car wouldn't be parked there, or would be easy to drive around.    

By your argument, it would be better for everyone to drive to the post office to pick up their mail rather than having the post office deliver it.

I think we may be going back to that.  That is how it was for me, growing up in a small town.  UPS wouldn't deliver; too small a market.  The USPS would deliver, but only to the post office.  People had PO boxes and picked up their mail in town.  It didn't take as much gas you might think.  Most people didn't check their mail every day.  And everyone knew everyone, so you could have a neighbor pick your mail up if they were going into town.  Many people had their mail delivered to their office PO Box.  A secretary would go down to the post office daily, and pick up everyone's mail.

I'm not convinced and would like to see some data.  Googling "energy efficiency online shopping" turned up lots of links to efficient appliances but only this item on the topic at hand:

For example, for each book sold, the online retailer Amazon.com uses just one-sixteenth the energy to operate its buildings that a traditional bookseller uses. Internet shopping also uses less energy to get a package to your house. Shipping a 10-pound package by overnight air -- the most energy-intensive delivery mode -- uses 40 percent less fuel than the average roundtrip drive to the mall. Ground shipping by truck uses just one-tenth the energy of a trip by car to the store.

In fact, each minute spent driving to the mall uses more than 20 times the energy of a minute spent shopping on the Internet. Online shopping eliminates the need for car trips and reduces congestion. Already, nearly 40 percent of people with Internet access say they go to the store or the mall less often.

The article, however, is dated 2000, and gives no sources.  It also touts just-in-time delivery.

Along with downloads, Amazon's used book network is an energy saver.  Everything I've ordered there has come via regular mail, not FedEx or UPS.