Almost everyone has experienced it: You're smoothly navigating a grocery store with your shopping cart when, suddenly, it squeaks. Quickly, one wheel rebels and spins erratically, and you find yourself struggling with the cart as if it were a stubborn animal.

Why does this issue seem to plague grocery carts? The reason is simple: Unlike carts in pharmacies or clothing stores, which usually carry lighter items and stay indoors, grocery carts endure heavy loads and face the harsh outdoor environment.

This exposure to rain, snow, collisions and debris — especially in parking lots — takes a toll, particularly on the wheels and the caster plates attaching them to the cart, which leads to malfunctions. According to CNN, this wear and tear, coupled with the high replacement cost of more than $200 a cart, explains the frequent cart malfunctions.

So, the next time you wrestle with a wobbly grocery cart, remember it's a small price to pay for the convenience of hauling your heavy groceries. It's also a testament to the unseen battles these carts endure in their daily parking lot adventures.