Social anxiety and introversion trumps any culture. Expressing gratitude even when it's to be done out of politeness takes effort.How are they so embarrassed to say something as simple as a thank you
Calling a stranger or even an acquaintance by their given name when you know their family name can come off as being too familiar or even rude.or the most common one I've seen would be calling someone them by there not-family (first) name.