In most western European countries, we have a form of politeness to adress either customer that we have not worked for a long time with or senior management :
Vous / Usted / Sie (respectively
French, Spanish & German) also known as T-V distinction.
Due to globalization and English as its lingua franca, the
Vous / Usted / Sie is slowly getting replaced by the
You, which can be translated to
Tu / Tú / du.
I had this conversation with several colleagues over the years. Some are adamant that we should stick to T–V distinction because it will implicitly makes the customer feels , that we are only acting in a commercial capacity , implcitely shielding us from harassement from the customers by reminding them we are not their "friends", which can be mistaken with
Tu / Tú / du and its familiarity.
Mine and some others ex-colleagues/friends have evolved, thinking that regardless, of using the T–V distinction, it will make no difference, and that if the customers feels he is right about something, he/she will do what is necessary go what him/her heard, even nagging you the hard way.
We'd better make the customers feel heard and respected but keeping a friendly distance nevertheless (e.g Marcus Aurelius) regardless of using
Tu / Tú / du or
Vous / Usted / Sie.
Having dealt with customers, some easy, some just plain terrible, I know I'm right but I have a hard time explaining it in a really short way.
If you have in any way something shorter than what I wrote above, to explain it to my current colleagues/junior staff, I'm all ears.