Besides, due to their greater weight, you can count a bucket of coins by weight, vs a less reliable dollar bill counter.
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Back when I was a kid, there was a chain of restaurants owned by Horne and Hardart known as "Automats". The restaurant had a wall of tiny door separated by category (mains, deserts, etc.). Each had a price in multiples of a nickel. When you dropped the appropriate number of them into a slot, turn a knob and the door would pop open giving you your food. They had cashiers who would change dollars into nickels all day long. They would scoop a handful of them, shake their hand, maybe throw one back and invariably give you the proper number.

Years later, when I was in college, the photocopier in the library took nickels. I had a "bright idea" and went to the school cafeteria (expecting an argument from the cashiers about changing $5 into nickels), The cashier, without blinking, started throwing handfuls of the coin into a paper bag with an awesome display of nonchalance. I asked her if she had ever worked in an Automat (the chain had closed years earlier) to which she answered "How did you know?".

en.wikipedia.org - Horn %26 Hardart
YouTube: Just Drop it in the Slot; a Look at the Horn and Hardart Automat and its Legacy (alan wasenius)

Jeff