Blueshoes, I think there was a study done on it that demonstrated that it was having a very negative environmental impact.
I suspect that depends on the delivery. A Tesco van tends to be full and is delivering to many houses so is reducing journeys. Amazon deliveries etc tend to increase them, as they often have many journeys with hardly anything in the vans.
I am simplifying, and have no references for this, but that is what I read a while back.
The point is that car driving is not better or worse than non car-driving in environmental terms when comparing 1 individual and another. I suspect many non car-drivers have a lower carbon footprint either because they are 1. environmentalists so are making other efforts anyway or 2. poor and so consume less and do less.
If someone drives 2 miles to work and I go 20-30 miles on a train, then I am not doing well just because I have no car. People have to think about all of their transport behaviour.
The carbon reduction stuff I got in the post also said that transport distances are fairly irrelevant to the carbon footprint of food, which I was surprised by.