The Supreme Court ruled and Congress ratified into law that once a copyrighted work is sold, the owner gives up the right to control resale. The specific case was book publishers who added a disclaimer that the book couldn’t be resold cheaply after purchase.
Of course you don’t “own software” like you don’t own the right to distribute to reproduce a book you bought. This is about resale rights.
https://en.wikipedia.org/wiki/First-sale_doctrine
The Supreme Court ruled and Congress ratified into law that once a copyrighted work is sold, the owner gives up the right to control resale. The specific case was book publishers who added a disclaimer that the book couldn’t be resold cheaply after purchase.
This is exactly what Steam prevents.