Who cares really, we are nice to each other, pilots or controllers.
Pilots often greet ATC with a "hello" in that country's language.
And controllers, often return the greeting in our language.
xxx
Has been like that since long ago. At least on VHF...
On HF, we tend to remain somewhat more procedural, initial call etc.
The issue is not "being professional or not"...
Concentrate your attention to your professionalism in your job.
Not about ridiculous details as this is.
xxx
Chau... (South American Spanish for "ciao")...
Happy contrails