What commonly happens when school or transit buses pull out from a stop, according to the manual?

49 CFR 383.117(a)(6), operating practices and procedures not otherwise specified; AAMVA CDL Manual Section 4.3.3 (p.4-3)

Mirror strikes and side-swipes when pulling out from a stop are a recognized, named failure pattern in the manual, which is why drivers are told to know their bus's clearance and watch for poles and tree limbs at stops as well as traffic.