An insistence upon eggs for eruv tavshilin

I overheard an interesting halachic question on erev Shavuos. Someone did not have matza for eruv tavshilin, and she wanted to know if she could use challah instead. The answer was yes, but I could see why it is a question. Certain common practices in Judaism have been ritualized, and even if not, the common setup in one's home is often to use particular items. And if all one sees is matzah and egg to make an eruv tavshilin, then one has a question whether other items can be used; and even if other items would satisfy the halachic requirements, if one does not know the specific requirements, how is one to know what would fit the bill?

Nowadays, a fairly common practice is to use a hard-boiled egg for the cooked dish. This would appear to be an innovation. As the Aruch Hashulchan writes, in Orach Chaim siman 527, seif 13,

"And know that most of the world places an eruv tavshilin using cooked meat. And when Yom Tov falls out on Thursday and Friday, such that they place the eruv tavshilin on Wednesday, in most instances it {the meat} becomes spoiled by Shabbos, and the eruv is thus nullified. And therefore, there is upon each individual to be careful upon this. And therefore, we are accustomed to place {as eruv tavshilin} a cooked egg. For an egg does not spoil {as quickly}. And the common folk are not experts in this, and many times we have seen that when they go on Shabbat to take the cooked meat upon which they established their eruv tavshilin, it is very spoiled, and they cast it outside. And therefore, there is to be extremely careful in this."

This seems to be his innovation, where the majority of the world does not do this. The same appears in the Ben Ish Chai (from about the same time), parshat Tzav, letter Aleph, but not in the beginning of Tzav, but under the halachos of Eruv Tavshilin:

"One is required to make an eruv {tavshilin} with bread and a cooked dish... And the cooked dish, it is good to make it out of hard boiled eggs, for these last in these {geographical} locations which are hot, while meat does not last in the time of heat for two nights and two days. For if Yom Tov falls out on Thursday and Friday, there needs to remain a piece of meat for two days and two nights, which is until the night of Shabbos. And therefore, it is good to make it from boiled eggs, for these last and do not spoil."

I think it very interesting that many people would wonder whether something other than an egg can be used for eruv tavshilin, since to deviate would go against common practice. But meanwhile, common practice used to be cooked meat. And in general, many different sorts of cooked dishes were mentioned and discussed in halachic sources.

Nowadays, there would seem to be no need for this halachic innovation. In their times and places, they did not have refrigerators, and so meat would not last that long. However, we can refrigerate meat, and we commonly do so.

I did not see any mention of specifically matzah over challah -- all that is mentioned is pas. Of course, without seeing any source inside, we could suggest all sorts of reasons this is better. My fear in doing it is that people would take an attributed yet false reason and use it to maintain the requirement long after it is no longer necessary. (I think this happens in other places in halacha.) But some suggestions:

1. Just as eggs can last that long, matzah does not become stale over a three-day Yom Tov. (We could enclose challah in plastic bags, though.) And especially if one wants to use the same eruv for Succos and Shemini Atzeres.
   
2. Indeed, common practice for an eruv {/shituf} for carrying on Shabbos is with a matzah, because it lasts all year and you need not replace it from week to week. Perhaps it got transferred from one to the other.
   
3. As a heker so that someone notices it when cooking on Yom Tov for Shabbos.
   
4. As a heker so that someone does not eat it early.
   
5. It needs to be a matza for Pesach, and it extended from there to other chagim.
6. Machine matza is somewhat cheaper than a challah roll.
   

Note: Not intended halacha lemaaseh. Consult your local Orthodox rabbi for any practical questions.