Are delivery workers really a vulnerable group?

I honestly don't think so. At least I definitely wouldn't dare to offend them. They know my address and are holding my food.
I usually am quite friendly with everyone, regardless of who they are or what job they do.
I often tell delivery workers, "Just leave it at the door, thank you," because I think they have a tough job, especially on rainy days.
They work in the wind and sun, so I try to be understanding and considerate. Sometimes if they deliver late, I just call and tell them to deliver it earlier.
But today, a delivery person really made me angry. It was that kind of frustration where you're clearly upset but can't really show it—it's really uncomfortable.
He accepted the order, probably a newbie, and couldn’t find my neighborhood. He called me, and I gave him directions. He responded by hanging up on me, then I looked at the map and saw he was just circling around.
I called him again and explained how to get here, but he got impatient. He hung up on me again after just a few words. I made at least five calls to him. The delivery was half an hour late. I really held back my anger—I didn’t say anything rude in the end.
After all, the food was in his hands, so I really didn’t dare to offend him. So anyone who says delivery workers are a vulnerable group—who dares to offend them? Plus, their wages are probably higher than many regular jobs!