It is a culture.
Reminds me visit to Spain. That was a generation ago, but doubt it changed.
In Barcelona lot of people go for lunch to bars, who have small front opening, but long bar going to the back and only few tables.
So people eat the lunch and all the napkins go on the floor. At the end of lunch hr you basically have napkins on the floor up to your ankles.
Our friend coming from different culture was leaving his napkin on the plate, what made the waiter angry, becouse he had to drop the napkin on the floor.
Bare in mind that all got cleaned within hr after lunch is over.