I volunteer in a charity shop that sells mainly books and music.
All the volunteers fit into the categories of - old/retired, unemployed or unable to work due to health problems. We have one part-time manager.
We do throw things out, but much less than we used to, the items that we are unable to sell are sent to a company for recycling and we are paid for them.
Most of the donations are of good quality. We can't sell books that are dirty or falling apart - they get thrown out.
We also sell on-line and we have some amazing books for sale.
Newbie - if this charity shop is throwing stuff out it 'may' be that there is a reason for it. If it is being dumped where it shouldn't that is another matter - I think that it is illegal.
If there has been an approach to the shop management and they have not been willing to discuss the matter go to the head office. It is unlikely (but not impossible) that this is a franchise shop. There are various financial benefits given to charity shops (I think that they get rebates and stuff) but I think this only happens when it is actually run by the charity.