(This is mostly taken from my forum post on Japanese bicycle culture, though edited and expanded.)
Back in 1997-1998 during my year at Tohoku University, this is what I observed in and around Sendai in regards to bicycling and transportation:
In and around the downtown area, sidewalks were built wide enough to have separate lanes of travel for bicyclists and pedestrians. Bicyclists traveled about 5-8 miles per hour on heavy, but comfortable bicycles. Stations had parking for bicycles, for a fee, though as a cheap college student I simply locked mine someplace far away not to get ticketed.
In residential areas, the roads were typically very narrow. Typically, no sidewalks were present and houses had concrete walls built up to the edge of their property. Utility poles etc. were built up the edge of the street and there was no on-street parking in most places. Pedestrians and bicyclists traveled along the edge of the road and cars and buses had to pass them. Many roads had blind corners, and round mirrors were set up on poles. These are all conditions which required cars to slow down, naturally. A bicycle actually can travel about the same pace in such situations.
On busier thoroughfares, sidewalks were built, but often more narrow than in downtown. Bicyclists and pedestrians had to often politely pass each other there. I couldn't stay on the sidewalk, as it was just too slow for me.
In general, the roads were more narrow, buses, delivery vans and taxis sometimes obstructed the lanes, and due to the frequency and volume of traffic, people were generally more patient getting around. Not too many bicycles were on the road, but people were used to sudden stops, and the drivers seemed safer.
Getting a license was harder and required an actual course. You just don't pass a test. I'm not sure this made for better drivers necessarily.
A lot of people got around on scooters and smaller cars, because owning an large car is expensive.
Parking was rarely free, except at stores out in the suburbs. The car often loses its measure of convenience when shopping. Shops accommodated people carrying appliances home via the bus or train, by adding straps and handles to boxes for you.
Gas was expensive. Also, most highways (if not all) were expensive toll highways. Older cars required annual inspections, which I'm not sure has changed.
No school buses. Kids bike to their neighborhood schools, take the city bus, or train. Kids grow up with bicycling and public transportation.
Taxi use is common. They're expensive, but you can get around quickly town if you are short on time. If the weather is bad, you have a commute alternative.
The minimum driving age was 18, and not too many older people needed to drive. At the university, people drove, but I don't think many of them did. I saw more scooters and bicycles in the morning coming to school than cars. Anyway, the worst drivers (young and impulsive, old and confused) were off the road.
Talking on the cell phone and driving one-handed was made illegal back then. It still is. A headset is required to talk and drive.
Bicycling along highways probably was illegal, never checked. Out in the country, cycling seemed more dangerous, especially on major roads not expecting bicyclists. Of course, most people don't bike city-to-city, they take the train.
On my fast road bicycle, I road on the busier roads instead of the sidewalk. I got yelled at once from a tough-sounding guy one time waiting for the light on a busier street. But I rarely had trouble or got honked at, even in spandex. I rode without a helmet. I got in two accidents, both my fault. One was with sticking an umbrella in my front wheel spokes, the other was hitting a pedestrian crossing in front of me in a crosswalk.
The main difference in Japan and the U.S. is how the roads in the cities are built. Don't be surprised more people drive when you build wide roads, provide free parking along streets, instead of providing wide sidewalks with paths for bicyclists. And if roads are designed for 30+ mph traffic flow, don't expect people to want to bicycle on it. If there is no close place for people to bicycle to, then obviously people will take their car. Neighborhoods need to be zoned to include more restaurants and convenience stores.