That's such fucking cap bro.
The difference is that Zoro is much stronger and useful
Zoro is giving his life for Luffy in the rooftop, and thats Luffy's response everytime
"Zoro!"
"Hey, Zoro"
Or he simply doesn't care at all.
Meanwhile with Sanji: "Having Sanji with us is like having the strength of 1000"
Zoro: "So im worth 2000 ok..."
Just compare it to Sanji, look at the things Luffy was willing to do for Sanji to come back. Look at how Luffy seems to understand him, it's a much more deep friendship. I think Zoro lacks that moment with Luffy
Imagine if Luffy knows that Zoro took his pain in Thriller Bark and simply didn't told Zoro he knew, but then he reveals in the right moment. I think this could have a great potential for Zoro's character tbh