That's a different thing. I'd say thank you if they are around me and they are doing something for me. Would I say hi to the landscaper who is working on the g

That's a different thing. I'd say thank you if they are around me and they are doing something for me. Would I say hi to the landscaper who is working on the garden while I was walking on the path? No. Unless we know each other, a nod is all fine.