They are interesting for a variety of reasons. One of which is, while some are similar in function to, say, the "handicapped tag" that gets you pick of the best parking spaces in the United States, they are mainly enforced through social convention rather than law. This gives the symbols greater reach than laws, encouraging helpful behavior that can't be effectively legislated. Because Japanese culture is based on social harmony and mutual respect for norms, they're actually effective.

Secondly, because they are enforced by social convention, they can be very abstract which helps to reduce stigma. The aforementioned handicapped sign is clearly an abstract silhouette of a person in a wheelchair, which is very, very on the nose compared to a butterfly, clover, or heart. Similarly, the bicolor chevron indicating "new driver" (which I first encountered as a roll-up item in the Katamari Damacy series) is a whole lot less obtrusive than the "dunce cap" worn by driver-education vehicles in the USA (typically, a large sign or signs reading "STUDENT DRIVER" or similar mounted on the roof of the car). American drivers would prickle at having to have something like the "dunce cap" on their vehicles for a year after getting their license, but if it were an obvious but unobtrusive and abstract symbol like the chevron, public support for requiring the symbol on the vehicles of even newly licensed drivers (probably a good idea) would increase.