
Other mistake: Dante and The Agency both have extensive photos and videos of the team's previous exploits. Trouble is that most of it is simply stills and footage from the previous movies in the franchise, often occasions when nobody was around with a camera to witness and document what was going on, certainly not at the angles we see.
Answer: Because it is such a small town that the school system can not afford buses for grade level so they have to share them, plus it has comedic value as well.
pross79
Small town schools are usually K-12. The other older "cooler" students drive to school or get ride with their friends.