Why does the US Postal Service use costly materials to make stamps

USPS Raising Cost of Stamps, Other Services in Search for Revenue

First-Class Mail International

My stash of old stamps is beautiful. Why make them unnecessarily obsolete?, Dale Berning Sawa

Beware Surge in Counterfeit Postage Stamps ​​

Is the US Postal Service losing money on forever stamps? - Quora

How to Send a Letter or Postcard

USPS is hiking the price of a stamp to 66 cents in July — a 32% increase since 2019 - CBS News

Postal Services International Student and Scholar Services

Is there a way to get mailing stamps at a reduced cost? - Quora

How is it the U.S. Postal Service has such low letter postage for

Price of Forever Stamp on the Rise Again

USPS is hiking the price of a stamp to 66 cents in July — a 32% increase since 2019 - CBS News

Stamps.com: How It Works for Small Businesses

How does the postal service know the value of each and every stamp