True/false questions are favored by educators first and foremost because they take little time to construct, but also due to the fact that tests comprising of such questions are very easy to grade. Many see the results obtained with the help of true/false questions as dubious because of the high probability of a learner guessing the correct answer. However, in fact, the chances of getting a passing grade while relying purely on guesswork are slim, provided that the test contains a sufficient number of questions. Like with other concretized questions, answers to true/false questions are harder to guess correctly than those to multiple choice questions.
This being said, course authors often do true/false questions a disservice by not putting any effort into constructing them. In addition, incorrect answers to true/false questions give no indication as to what knowledge the learner is missing and the reason they have answered incorrectly.