you guys

i finally figured it out

the checkout belt at the grocery store

there's a sensor on both inner sides beside the belt nearest the cash register and the belt stops when it's interfered with

so every time a pomegranate (buy me some, please) or fragile piece of glassware gets to the end of the belt, it stops before smashing into a puddle of sweet red juice or a pile of jagged pieces

then when all the food is off the belt it just keeps going
until the register person puts one of those dividers down and it stops!!!1!!magic!!!!!11!!11!!!

i don't have enough pointless chapters like this