Address return frustrations

I can’t understand why you CAN NOT put your full address on the label you print when we are trying to return merchandise. I went to the USPS today and I decided to just pay to mail the merchandise back to you BUT the post woman asked me do you have the zip code?. I said it not on the label? She said is it on any of the paperwork you have and to my surprise there were no zip codes except my home address zip code. Please put your zip code on the return label so it isn’t so difficult to return merchandise. The USPS in AZ does not use the bar code reader to enter the address if that is what your answer to me is going to be. They require that we print the zip code on the box so they can enter into the system. They are also not going to lookup a zip code. I had to go back to my car and get my phone and use USPS zip code to look up your zip code. She only gave me 3 minutes to do this because they were closing. This was just 3 minutes of stress I didn’t need because you can’t be bother with printing 5 digits after your city and state. I just can’t understand why any software programmer would not include the zip code when printing a return address unless you are trying to make returning merchandise very difficult on your customers.