My understanding is it helps establish structure to the online learning environment for the students (the teacher is actually in a classroom), gives access to most classroom resources, and establishes a level of accountability and professionalism.Although... why?
When it comes down to it there are a lot of teachers who since the shutdown have been enjoying a very long vacation getting paid full salary for about 1/10th of the work.
My nephew's teacher (he's a third grader) was holding Zoom meetings twice a week for one hour. That's a total of 2 hours contact with her students a week. She was also rather difficult if not impossible to get ahold of for additional assistance when needed. There was really no teaching going on and he struggled. Luckily his parents were able to assist and pay for a private tutor.
Most school districts are facing multiple lawsuits due to failure to provide various aspects of education...my nephew's online learning environment is a typical example of this failure.
My wife's school was actually advised by their attorney to have all teachers teaching online from the classroom this year for this very reason.