Weight and size correlate with fuel/energy usage. There's also availability of access/parking space and time to access the packages. If you don't deliver more than a bag each day, a car is not needed. If you don't deliver large things, a van is not needed. Etc.
So if you already have a van, it didn't matter if it's half loaded or full. But if you're getting new vehicles, 1 bike doing 3 trips may be way cheaper over time than 1 van.
What I would love to see is a ban on advertising in the mail. It all just ends in the bin. Such a waste to see those poor postal people sorting trash flyers for each house. Has to be soul crushing for them. And all I do is skim it and chuck it and get annoyed I had to sift through to find real mail…
Some sort of “opt in” code… that companies who sent bills and places I signed up to could use. But that would block unsolicited communications…
So if you already have a van, it didn't matter if it's half loaded or full. But if you're getting new vehicles, 1 bike doing 3 trips may be way cheaper over time than 1 van.