In your buffet example, you have some personal responsibility to those groups, as members of those groups. Gobbling the goodies isn't unethical so much as uncouth.In my Sunday School classroom, Susie often doesn't ever get the opportunity to use the purple marker unless I make and enforce a rule. There are multiple kids waiting for the few purple markers, the "waitlist" for markers is broken - Susie can claim it first, but if Billy hands it to his friend Robert, Susie still doesn't get it, and eventually we run out of time in the classroom. So we don't hold what we aren't using - there is no reason for Billy to hang onto a marker he isn't using until he needs that marker. When he wants it, then HE can wait for it.
Realistically, what happens with second graders - and with a few adults when talking about resources- is that some kids only want to color in purple. Other kids want to horde resources - some because they have concerns about scarcity, others because it annoys other kids (about half the Billys never use the purple marker in the end), some because they can - we try and teach a model of sharing resources, using only what you need, relinquishing what you don't need when you no longer need it - as well as making due - purple may be preferred, but yellow and orange are lovely colors as well because those are the values - values feeding into ethics and morals - that we hold as a religious community. I've been teaching second graders for a decade, and I've had a few kids who were seriously challenged with the idea that they couldn't/shouldn't grab ALL the glitter or every fuzzy pipecleaner - and thank god we got rid of snack - one of those kids would make snack miserable for everyone.
There is another example of this that came up in my life. I was taught that if you went through a buffet line early (not a restaurant, but a private event) you took small amounts of food to make sure that the people who came through last got to eat. If you went through late, you got what was left, which often meant you got "first dibs on seconds during your first helping" - the downside is that the chocolate chip cookies would be gone and you got stuck with the oatmeal raisin. I am involved in a girl scout camp where middle school and high school girls do tent camping under the supervision of some adults. Its girl scout tradition that the adults go first as a sign of respect. A few adults (those not involved in buying and preparing the food, who are well aware that there are not enough chicken legs for people to take three - its generally the ones that were there to increase the adult to girl count to meet the safety regulations in exchange for free camp for their daughters) were loading up their plates to heaping (and throwing out half the food they took) - while the girls at the end of the line we ended up making sandwiches for so they wouldn't go hungry. We buy plenty of food, but we assume people will be reasonable when they help themselves - and we are twenty minutes from a grocery store with a hundred girls - you don't just go grab some more food. And, the camp is designed to be affordable - we have plenty of food - we don't have plenty of extra food - that adds to the amount we'd have to charge for camp. There is no rule that says "going through a buffet you take a reasonable amount of food and keep in mind that there are 120 more people coming after you and this is all the food there is" - but it isn't ethical to let an eleven year old not have a brownie because you took three and threw out one. Next year, we are going to need to spell out buffett manners - not for the girls - for the adults. Once again, using resources well and consideration for others are Girl Scout values.
Both of these are examples where we shouldn't need a rule - people should be reasonable. And if one person is unreasonable - or has a real need for their behavior - the system still usually functions. But the behavior of one person is modeled by others (oh, I can take three chicken legs because she did - oh, Billy always grabs the purple marker, I'd better grab it first, - oh, I'm going to need to walk a reservation because that is how you get rooms), and eventually the system breaks down.
(And yes, we should have more purple markers. But they come in boxes with the orange markers and the yellow ones - and the cap gets left off them or they end up in pockets, and by the end of the year I have a tub with 20 yellow markers and two functional purple ones)
Teaching 2nd graders not to be thusly uncouth is great training.
As is pointed out frequently on this board, this isn't really club; it's a timeshare. It's a timeshare that you spend a large amount of money buying into and maintaining.
Your first ethical obligation is to yourself. In a first come, first serve reservation system, there is no sharing.
The better example than purple markers is teaching 2nd graders that they must share their chairs during musical chairs. That's a fine value to teach generally but doesn't work well in the specific example.
A first come, first serve reservation system is much more like musical chairs. I have no ethical responsibility whatsoever to other chair seekers. More to the point, unilaterally engaging in such ethics will only lead to the very predictable outcome of you being the one without a chair.
I doubt very seriously DVC cares much about walking. It's a rule in customer service that 20% of the people create 80% of the problems. In this case, walking is an outlet to mollify the 20% at virtually no cost to DVC or the system as a whole. My guess is that DVC views walking much the same way as WDW considered FP- runners that were able to take advantage of the system. WDW only ended that practice when they had an interest in changing the system to FP+ and making FPs more fair was certainly not their primary goal for the change.