The irony is also that if people want to continue to play your game they won't trade it in and online play is a good way to keep people playing. The feature itself discourages used sales. It's the I-beat-this-in-three-days games that get traded in right away.
If the online wasn't enough to keep the game for then the 2nd hand buyer probably won't use it either. Which means who cares if there is no online code/access.
I'm saying that game servers cost money and people that buy the game new supports those servers. It's built into the cost of the game to keep those servers up and running. When Used game shops sell games that focus heavily on online play, the server is seeing users that didn't pay in for the right to use the server. That's not fair to the dev/pub regardless of who they are.
The only way your car example would fit is if there was a Car sale with a $1000 rebate on all (let's say) Toyota's and some guy just bought a Toyota on Craig's list and is now complaining that he doesn't get the $1000 rebate. If you wanted the rebate, then you should have bought the car from the dealer, not a private 2nd hand seller.
if 2nd hand gamers want to access the online portion of games, then they should either purchase the game new or buy an online code. Servers are not free, and dev/pubs like EA should have to bear the cost of the servers for people that didn't even help to support them in the first place.
And I'm not suggesting that all used game sales should give a portion back to the dev/pub, just the ones that require continued support and cost to the dev/pub, such as titles that use online and have dedicated servers to provide it.
Gamestop for example will Sell a new game for $50, buy back the same game a week later for $25 and then resell it 20 minutes later for $45. So I don't feel any sympathy for a company such as EA decreasing the value of a used sale purchase over the purchase of a New copy of the game, especially when companies like GS will purposely order low amounts of copies to they can push all their used/open copies out the door to unsuspecting customers that think they're getting a deal.