Vertex - understanding why we dont need transportation fields

We are currently implementing JDE e9.1 into the states and will be using Vertex Q series.Can any one shed light on the following please.

we need to ensure that we end up generating the correct sales tax.  Our understanding of the US sales tax is that the tax is calculated where the ownership of goods are transferred. However, surprisingly there does not appear to be any transportation fields passed in to Vertex to determine whether or not the goods are being delivered or collected.  We therefore need to understand if there is any ‘assumed’ logic built into the use of the address book records to help to determine this.  For example, if the ship to and sold to records are the same is