Heman, the first 3 scenarios would probably not fall under abandonware, but more as of GPL or GNU licenced, as the Copyright owners gave the general public free reign to that specific item. * providing the public follow the terms of GPL or GNU licence provisions* thus being free for all to use and enjoy.
In the last case, "True Abandonware" where the company closed it's doors without releasing the item. It would still be held under Copyright. Those copyrights could possibly be held or maintained by the Bankruptcy courts, until they are "if at all" distributed to the creditors to who the orginating company owed Funds too. They can also be sold off by auction if they are deemed valuable and worth a monetary value. The funds from the sale would then be distributed amongst the creditors. This all depending on the courts decisions.
As for Trash.. Trash is knowingly thrown away, there for it would fall under abandonment, as you willingly tossed it away. But it could also be argued if the trash was placed in to a recepticle, the owner of said recepticle would be the owner of the trash. * possibly including "Intentional transfer of ownership" if the owner of the recepticle is not the same as the original owner of the deposited trash. California has private refuse companies Who own the recepticles, once trash is placed in them, technically the ownership and responsibility of disposal falls on the owning company.
Also for those who think a person breaks a law or can be classified a criminal only when caught. The minute you Break a law wether it is known by law offocials or not, you have violated a law. While technically one is Deemed innocent until proven guilty in a court of law In the US, If you know you broke the law, you are still guilty of a criminal act. Even if it never comes to light. If you tell a lie, is it still not a lie even if never discovered?
We all have a bit of larceny in us, it's human. It's up to us and our moral fibre to decide for ourselves what is "our acceptible level". While Society will judge people when caught, their consciences will judge them when not.