I don' know, but I can assure not enough of them. They have had their hands tied by government officials who have no clue about education passing laws, by whiny parents who don't teach their kids proper behavior and then complain when a teacher enacts some restrictions, and those parents who swear that their little Cayden or Emily couldn't possibly be failing because they do all their work because they told them so and said the teacher hates them.
That's like asking how many grains of sand there are on a beach. We are all individual people - some are strict, some are not. Take what you can get - learn from the rest.
No one can answer this question but I think that teachers should be strict in the classroom while teaching to maintain the decorum of the classroom and due to the strictness of a teacher, students can perform better in their academics. In the free time, teacher should be polite with their students so that they can ask their queries so it depends on the teacher to act according to the situation.