I can sort of see the similarities, the 'original' retailer buys from a distributer and makes a profit selling to the 'original' consumer.
the consumer then sells his game as 2nd hand (developers don't get a cut here), and the 2nd hand retailer sells it on again (again no cut for the devs) to another buyer and so on.
so for all these sales backwards and forwards, the devs and or publishers only get one cut.
I suppose it's almost the same for rental games, although I think rental copies of games are more expensive to get hold of (more of a cut for devs)?
other than some sort of a licensing agreement between used game sellers and large games publishers/companies (MS, Nintendo, Sony, EA or similar) where the 2nd hand retailer (like Gamestop or similar) pays a fee to be allowed to resell games, DLC would probably be the best way to get a slice of the pie from the process.
I don't think 2nd hand sales/rental and piracy are morally the same, but I can see how games publishers could think they're getting a bum deal.
lol even priated games probably came from a legit (purchased) source 
devs get the same cut from that and the torrents as they do from 2nd hand games
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