But, if you're taking a copy, then passing the original on, there are now two copies in existence. The copyright holder has only been paid for one of them.
Taking a copy for your own use (back up for damage etc.)seems fine to me. But if you don't retain the original I don't see you have the right to retain a copy.
If you donate the original to charity, but retain the copy you've made, the next person to buy it from the charity shop may do the same. there's now three copies in circulation, for which the original artist/copyright holder has been 'stiffed' for two fees. This can go on increasing ad infinitum.

It is NOT ethical. (answer to original question).
It is, however, common practice.