It is true that exports are just sales and yield revenue, not income. Exports are just sales because these are purchases of rest of the world from the Domestic Economy. Accordingly, exports yield revenue (receipts from sales). These do not yield income.
Because, income is in the form of rent, interest, profit or wages. Exports do not yield any of these directly.
Note : It is out of revenue that a firm distributes incomes to the owners of factors of production.
