Hi Ken,
Costa Rica does have a great bus system for getting around town, around the region, and around the country, including to the coast. Buses are on-time, frequent (especially in the Central Valley), and modern. Many Ticos don’t have cars or just one per household, so a lot of people take the bus. The system works well. Taxis are also plentiful and pretty reasonable in price. Many expats get along fine without a car. That being said, having a car makes things more convenient and you have more flexibility to explore more rural and off the beaten path areas, including in the coastal communities. Something you might consider is renting a car for at least some of the time you are there to make a comparison. You can also walk as much as you want here. In many areas all you need for daily living is within walking distance. Great exercise. I have a friend who lost 40 pounds over six months – just by walking.