Why does the AAMVA CDL Manual direct bus drivers to keep the aisle clear of carry-on baggage?

Passenger (P) Endorsement • Free CDL Practice Question
Regulation

AAMVA CDL Manual, Section 4.2, p. 4-1

Why This Matters

An aisle is the only path to the exits during both a normal stop and an emergency. Loose baggage there can cause a fall during routine boarding and can turn a fire, crash, or evacuation into a far more dangerous situation for everyone on board.