How would you install a meter for a mid-span tap?
At the weather head bugs. Or the splice box/disco mounted on the side of the home.Sure they could. But what would the typical service delivery point be and where would it be (I'm thinking residential here) if their meter base goes away or whatever the metering is is moved to the street? I'm sure the POCO's wouldn't mind saying the service delivery point is a box at the street and the cable from there to your building is on you to provide. The meter base does provide some conveniences -- in most areas it defines the service delivery point which is the boundary for wire size jurisdiction, and it is a convenient utility disconnect for an electrician to use without having to get the utility involved (just pull the meter, but let utility know so they can reseal the box when you're done).
Many large commercial loads are done this way and have been for 40-50 years.Since deregulation, some places you own everything from the transformer all the way to the building. Have seen metering on the primary side at the street in Arkansas just for a Wal-mart.