In person provides great interactive opportunities with the teacher, and classmates. That can give the kids more motivation and keep them interested in chess. That's one benefit. But is in person definitely better?
I don't think so. I have taught in person and online both for last 7 years. From my observation, online students are more motivated to learn and more eager to play in tournaments. That's more important than just coming in and showing attendance. I always try my best to make my online class interactive. I ask a lot of questions, so the students have the chance to participate. More participation, better progress.
One advantage for online class is everything can be recorded. Even if a student misses a class, he could watch the video and catch up. So I always have a long syllabus for online class. We can arrange our learning for the whole year. In person classes have to be cut into each quarter. So the knowledge might not be evenly spread out. We also need spend some time to repeat some lessons for each quarter because students always change.
Another disadvantage for in-person class is: there is no score sheet for in-class games, so it's not possible for the teacher to review students' games. Online games always have the score sheets which the teacher can review at any time.
Another issue with in-person class is that not all students can have access to an in-person class. I have students from everywhere, from east coast to California, Texas, to Canada. With internet, all can take my lessons.