There are companies that teach young execs good table manners. Apparently it's an issue that has warranted attention.
For many reasons, some people grow up without learning good table manners. Maybe it was a family that never ate together, ate in front of the TV every night, or, as PPs have mentioned, some have had to "guard" their food from others.
There were 6 kids in my family, but my mom was strict about table manners. We had to learn which utensil to use, how to sit, how to ask for something, and we even had to stay at the table when we were done eating in order to be social. After a respectable time we could politely ask to be excused.
I imagine that that kind of thing would drive some 21st century (and 20th century) kids crazy! Kind of sad, IMO.