Why are the research methods of sociologists different from those of most other scientists

Because basically, in the first place, both are from different fields. While sociology is more on arts, other sciences such as Physics, Biology and Chemistry are the hard sciences. Hard sciences means that the experimentation requires a very small amount of error, up to one percent. This experimentation uses materials which really expensive and harmful. Meanwhile on sociology, it requires a room of error up to five percent since some of its population is bound to different errors such as human errors, etc.