Do you return “misdelivered” mail?

Let me know if you all feel this isn’t controversial enough and I will move it...

I recently returned some misdelivered mail to my neighbor that I received by mistake. They were pretty shocked that I took the time to do it, and laughed saying they wish they had thought to do that in return for me because they have been receiving some of my mail for months and just threw it out 🙄. I always thought it was illegal to just throw away someone else’s mail—even if it wasn’t, I’d feel it’s common decency to attempt to make sure mail is delivered to the intended recipient. That’s just my personal take on it though.