This question is very culturally specific to the United Kingdom. Social and age deference is waning in the UK, this may be a matter of personal opinion as to whether that is a desirable trend.
Many people of "a certain age" in the UK were brought up to use titles and honorifics. Teachers are addressed as "Sir," or "Miss," and it was generally expected that older people were addressed as "Mr X," or "Mrs Y."
This expectation of courtesy was also expected from serving staff in restaurants and other service outlets. I have observed recently, that on three different occasions in recent weeks of having been addressed in widely different forms. On one occasion when my takeaway order was given to me, the server said "Thank you very much, Sir. Enjoy your meal." On a second occasion at a different establishment the food was served with a "Here you go, Buddy." The third and most recent was a "Ta, Mate."
While I am not overtly offended by any of these manners of address, it does seem to be culturally unexpected for a middle-aged person, to be addressed as "Mate" by an unknown teenager.
Would politeness and professionalism not dictate a more distanced or formal mode of address from staff (no matter what the age of the customer), or am I merely being "old fashioned?"