Multi round interviews are so frustrating

The area that I live in requires teachers to go through a first round interview with just admin, then a second round interview with admin and the grade level team you’d be potentially joining, as well as a few others such as the counselor, instructional coach, ect. I don’t really understand the purpose of a first round interview in this situation. I feel like there should only ever be a second round interview if there are 2 candidates who are difficult to choose from. Other than that, I don’t get why multi round interviews are a thing. Schools know what they want, so why put candidates through multiple rounds for one interview?