What is 'spare change' - surely there is no such thing

Change is just coins that have yet to be spent .
Maybe it is the carrying around of such coinage that is the problem.
The extra weight to the pockets for those that refuse to use a wallet or purse.
The noise created by the coins clashing together that grates on some people.
The lining of pockets ripped to pieces by the merciless rough edges of the 20p and 50p pieces

The germs and dirt on the coins that causes people to want to discard them into a hooooge bottle or 'change pot' or similar container.
Why do you not just put your change into your purse / wallet and then when purchasing items provide the correct amount of money ?

Or is that too much faffing and holding up of queues ???
If you store your change in a jar or some such ...when is enough and enough and you decide you need to cash it in ? Isn't that much more of a palaver taking that to the bank to swap into real money ?