When mistakes are made, there is usually some sort of loss. The issue is doing what is right when we are able to do so.
The weird suggestions here betray a strange perception of how we should live.
It is like finding a dollar on the side walk and finding a wallet in a restaurant booth. Yes, someone lost something in both instances, but in one, we have a practical way of resolving it.
A cashier gives one too much change, it should be returned. Our "gain" is the real loss of someone else, and if it is practical, we should return the extra money. Now, in this case, it is usually related to a specific cashier on a specific shift, and something that would be difficult to resolve by giving the extra change to the service desk the next day. That is probably not helpful given how the system usually works. However, if we notice it at the time, we should correct it as soon as we can.
It is not a matter of a balanced human system or of being recognised for it, but of being just. In even the small picture, it is likely a small matter, but it will show how we make choices.
He that is faithful in that which is least, is faithful also in that which is greater: and he that is unjust in that which is little, is unjust also in that which is greater.
He that is faithful in that which is least, is faithful also in that which is greater: and he that is unjust in that which is little, is unjust also in that which is greater.
If then you have not been faithful in the unjust mammon; who will trust you with that which is the true? And if you have not been faithful in that which is another's; who will give you that which is your own?