any hostel that doesn't take deposit from guests?

I've had that problem before in London. They 'fail' to grasp we have reserved a bed for them, and when they don't show up, they say why should they have to pay for it??? I try explaining that we held that bed for them, expecting they would show up, meaning we couldn't sell the bed to any one else. They would still stay I didn't sleep here, so why do I get charged?

I then try explaining it's similar to flying. When you purchase a ticket, the airline will take your money regardless if you fly or not. If you reserved a seat but didn't fly, you don't start saying to the airline "Since I didn't fly, why do I have to pay?" I still had one person who refused to accept that answer.