I got more flats in Rome than just about anyplace else I've ever ridden. I blamed it on the cobbles that just would hold onto glass. But, it has been a couple of decades, so perhaps things have changed.

Some parts of Italy have a celebration of ringing in the new year by throwing out the old, which can mean throwing out glass bottles. I spent new years in a small southern town called Uggiano La Chiesa, and at least one street was a couple of inches thick with broken glass on New Years.

Nonetheless, it is quite possible there are major cultural differences. When I was there, the Italians drank bottled water and wine out of glass bottles, but both the glass bottled water, as well as the wine may be something that one gets at a sit-down dinner, rather than swigging it as one drives along, then tossing out the window.

In fact, I think the "open container" laws in the USA encourage beer drinkers to chug their beers, then toss them out the windows.