Does the PO get less when I print my postage stamp online and drop off at PO?

[Theresafar]

Does anyone know? It’s tempting because I could save 50p on a small parcel but would it mean the PO do not get anything if I do it this way?

I read on the BBC website that the PO get just 6p from every first class stamp they sell so that’s why I’m curious but I cannot find any information. 50p is a lot to save, and with all the online selling that some do it must mean a lot more saving. Does it mean the PO get less or nothing at all, if I pay online and just hand a parcel over their counter? Surely they get something.