A final pic...I took this to show the braking mechanism on the big three-wheeled cargo bikes.
Note the pedal over the down-tube. That is the brake pedal. That activates a mechanism that forces the two big blocks over the chain stay to move forward (toward the front of the bike) to press against the rim. That stops the bike.
Same mechanism was used on the Indian-made bike pictured above.
Obviously this bike doesn't have a seat...on very hilly, cobblestone streets it looks like some folks have given up on riding these three-wheeled cargo bikes and they use them as push carts.