I was watching “I Love Lucy,” and Ricky and Lucy are getting a car to go cross country. Lucy says “the back seat of the car is empty so come with us.”
Ricky thinks Fred should pay for half the gas. But Fred and Ethel and even Lucy come back with the argument "Why should we pay anything since the back of the car goes where the front goes and they are going to California anyway, so Fred shouldn’t pay.
This argument seems faulty but I can’t quite figure out why
Well the added weight of Fred, Ethel, and their luggage would effect fuel efficency. Plus Lucy and Ricky are sacrificing space they could use for luggage.
There are two arguments I could make
This reminds me of a real-life example regarding hotel rooms. My sister-in-law and her husband were going away for the weekend to some conference. Another couple that they know slightly was also wanting to go. They asked if they could share the room with SIL and husband. However, since the hotel room would cost, let’s say, $80 for two, and $95 for four, the second couple wanted to pay only the $15 difference in the cost.
There’s a line between frugal and stingy, and that couple definitely stepped over it.
There’s also a bit of “make it worth my while” going to the original couples here (both in the OP and the hotel room story). Lucy and Ricky could have a romantic private drive, but Ethyl and Fred’s presence, while I’m sure welcomed as friends are cool to have around, takes away that opportunity. So what do Lucy and Ricky get out of the arrangement? Ideally, they pay less in gas money because they’re sharing a ride.
Ditto the hotel room: the friend’s presence might be fine, but it still means the first couple doesn’t get their own private room. What’s in it for them if they’re not at least getting a discount by having the second couple pitch in? If they split it, they’re all still paying less than they would for two rooms. Otherwise, the first couple is paying $80 a night for a shared room instead of $80 a night for a private room, and that’s just a gift, not a shared deal.
I hate to pay for plane tickets. I mean the plane’s flying to its destination with or without me. And I don’t weigh all that much. 
As I understand the specific situation o the OP—Lucy and Desi are taking a trip that they want or need to take, and they invite Fred and Ethel along for the ride, without any indication in the invitation that they would be expected to contribute toward gas, and with the implication that they are not really inconveniencing or costing Lucy and Desi anything by accompanying them—they should not pay for half the gas. But there are other situations in which it would be only fair for them to.
[nitpick]I very much doubt that. It would probably affect fuel efficiency. But not enough so that I’d change my answer above.[/nitpick]
As Thudlow Boink points out, the captain of the plane didn’t say, “Hey Leaffan, we’ve got an empty seat – why not come with?” 
Certainly, Ricky and Lucy’s invitation implied that Fred and Ethyl are invited as guests, but any good, polite guest would make an offer to contribute to costs. Also, what about other trip expenses? Does the invitation also imply that Luck/Ricky are going to pay for meals, accomodation, entertainment and legal expenses (when the cops pull them over and find that Ethyl is using the opportunity to smuggle 5000 hits of exstacy)?
Regards
FML
Carrying an extra passenger involves certain inconveniences such as taking longer to get ready, longer bathroom breaks, making compromises on where to eat/stay, not being able to use the seat for luggage, etc.
Well, Lucy and Ricky did ask them to come along, but the polite thing to do would have been to offer to pay. However, any fan of I Love Lucy will tell you that one of the running gags in the show is that Fred is cheap. He doesn’t want to pay for anything, and they are constantly talking about how Ethel never has new dresses and how they can’t/won’t buy a washer and dryer, can’t/won’t buy a dishwasher, etc. He is a cheapskate and he took the invitation only because it was a “free” trip. He probably didn’t expect for the Ricardo family to pay for all of his expenses but the actual travelling would have been something he wouldn’t have considered paying for since he didn’t ask to come along.
Wasn’t Fred Ricky’s manager? If not would Fred really pay for his own hotel room for a couple months just to hang out in LA.
Fred was the landlord. He was his best friend too, but also his landlord. I would think that he could have said something like, “I’ll come along to California with you! I can’t afford to pay, but you don’t have to pay rent on the apartment for the time we are gone.” Or something like that.
This argument also applies to movie and theater tickets, or anything which is designed for a large number of people to do something at once, and where not all places are filled.
And, actually, the argument you make is one reason why airplane tickets vary so much. The plane is going to the destination whether one seat is filled or if all seats are filled, and pricing is designed to try to get all seats filled.
But essentially, the rebuttal is the same: the fixed costs need to be paid for somehow.
Um, yeah. There was a in my post in case you didn’t notice it .
Thread-Jack: I had a friend a time ago who recommended we try a new golf course because he had a 2-for-1 green fees coupon.
…wait for it…(though you can obviously see where this is going)
Yep, he fully expected me to pay full price and so he could use the coupon and golf for free. :smack:
I had a roommate who thought he didn’t need to pay rent because I was already paying it.
Besides, the back seat was where LEETLE REECKY was supposed to ride!