Do you ever go to thrift shops? 
Of course yes!. I like them because  they are  retail establishments run by a charitable organization to raise money.
We have a few in our town and every once in a while I pop in. Sometimes they have really great stuff!
They really are as you said probably because they are a social enterprise in nature
I think some pretty large organizations run some of them. Like the Salvation Army, for example. They have a long history.
Yes, you can get items such as clothing, books, music albums, home videos, and furniture to buy and they are often donated by the public
Sometimes I donate clothes, furniture, and household items. You can get a tax deduction.
It would surprise you to know that many of the staff are volunteers