The 'dime' coin used to be a small amount of silver. Over the centuries, that coin is now made of cheaper alloys.
Depending on your age and limberness, it could be easy to walk away from that kind of coin on the ground.
A child might be elated to discover the coin and have it.
A small pet might need thousands of dollars of medical care (if it swallowed the coin and did not pass it).
Because a coin represents 'money', it is not generally considered to 'disposable'. There is even an expression; "Money just waiting to be picked up off the ground".
Some decades ago, toxic material was sometimes driven around on trucks during rainy nights. Trucks that leaked. It was simply a crime, to save the cost of legitimate disposal.
It is too easy to be lost to life, and not count cost of the things dropped or disposed.
Suppose you had a drink with ice. Enjoying all the drink, the disposable cup might still have some ice in it.
You would likely be best served in drinking or eating that ice. Even if it meant leaving it a while, and drinking the melted ice. People do not always have that choice. Putting the ice somewhere where water is natural might be a good second choice.
Separating then, the disposable cup from the water weight of the ice.
On the other hand, many drinks would become foul if simply poured into drain water systems or left as puddles on lawns.
There is a proper, legal, and good way to dispose of things. When the item is small and common, it could become easy to ignore. Like a dime on the ground.
A disposable cup that may have cost ten cents deserves some thought. Do we keep it for a while to have maximum utility? Do we put it dutifullly someplace where it will be removed? Have we taken clear thought to what happens next for that cup? Have we judged the contents left inside?
Everything we dispose goes some place. It's helpful to think about that before we even stand at the trash can.