Kamakura city issued an ordinance to ask for not eating while walking. It aims to prevent littered food from attracting animals and keep the street clean. When I visited the US, I envied to see people eating apples while walking. But I learned from CNN news that eating on street is being restricted in some countries. In Florence, Italy, the city government banned tourists to eat food while walking in the city's busy corners. This is to prevent the streets from becoming more crowded as well as for hygiene. Kamakura city does not fine those who failed to follow the ordinance, whereas in Florence violators have to pay the fine. In Bangkok, Thailand, this is a controversial problem. The city tries to find how to reduce the crowd while retaining the culture of street vendors.
It is considered to be a poor manner to eat while walking in Japan. We are supposed to be modest in public place. I think that Kamakura's ordinance is intended mainly to foreign visitors. You will notice that on subway in Tokyo those who speak loud are mostly foreign visitors. I somehow envy their unpretentious manner.