It would benefit all users to have a subcategory for running reports on ship cost for USPS Priority Mail: USPS Flat Rate Padded Envelopes in particular. Right now FRPE data gets lumped in with Priority Mail and there really is no good way to filter these from each other for independent reporting on shipments & ship cost.
As a business, we need thorough detailed information for accurate reporting on carriers, shipments, & costs. It would seem easy to implement this feature to provide accurate reporting on volume & spend % on specific subcategory shipping services.