Question

why do we need a post office​

Answer 1

This is why private parcel carriers like UPS or FedEx let post offices deliver packages for them a lot of the time: it reduces their operating costs and cuts down on how much they have to deliver. ... And unlike the postal service, they're not federally mandated to deliver mail to the doors of all US citizens

Answer 2

when the peoples want to send messages by the letter they use post office....