OK, I understand now. I remember the earlier discussion, but I’m not going to read it again, because I’d probably just use the same wording to try to explain this. If I start fresh, maybe I’ll say it differently and the message will get through.
The Tax Summary report includes both sales and purchases subject to various tax codes. Each half (sales or purchases) includes columns for the untaxed amount, the tax, and the total. The untaxed portions are called Net Sales/Purchases. The taxes are obvious. And the totals need to be called something, so they are called Total Sales and Total Purchases. That does not mean you sold or purchased the tax, only that the columns include the total amounts from sales or purchases. There is no more logic to it than that.
Your drill-down on the freight account from the P&L properly shows zero because nothing was posted to that expense account for that transaction. All of that line item went to Tax payable (or some other liability account if you didn’t use the default setting). That is what corresponds to the zero balance under Net Purchases in the Tax Summary for the GST 15% on imports line. All of such a line item shows up under Tax on Purchases.