Traveling in Thailand is not very difficult and can be a lot of fun. People usually get around in all kinds of ways. You can use the buses, trains, ferries, long boats, row boats, tuk tuks (skinny cars), taxis, cars or bikes to get around. When you get to an area you like, walking around is easy too. When you are in a place with small islands or long rivers, boats can be as common a form of transportation as road vehicles.
Most people in Thailand use public transportation. Barely anyone drives their own car but that doesn't mean there isn't traffic! The most common personal mode of transit is motorcycle because it is affordable and can weave through traffic easier. Many of the Thai people have grown up using the motorcycle or motortaxi. Ferry and boat travel is also fairly common. Biking is not so common and the infrastructure for it is poor, but this is slowly changing, as biking becomes more popular. My exchange friends and I will sometimes use an app. called Grab which is like Uber or Lyft in Asia, but most of my Thai friends prefer to use taxi and have never used Grab.