Because we are able to prepare food on Yom Tov, it is possible for people to find themselves in a situation in which they discover that essential ingredients for the meal are missing. Obviously they can go to their neighbors, borrow raw ingredients, and return them after Yom Tov is over. The last few Mishnayot in our perek relate to such transactions.
The last Mishna in the perek teaches that a person can go to his local storekeeper and ask for a specific number of nuts or eggs – that he intends to pay for after the close of the holiday – even though previous Mishnayot limit the permissibility of having him weigh meat (28a, b) or measure out liquids (29a).
The Tosafot Ri”d explain the difference as being whether the agreement appears to be a business transaction or simply a neighborly agreement. Weights and measures – especially when connected with a specific value (like the case in the Mishna on 28b: “weigh for me a dinar’s worth of meat”) – are clearly business-related and are forbidden on Yom Tov since they are “weekday activities.” Counting out a certain amount of eggs or fruit is an everyday household activity, which does not carry with it the stigma of commerce, and would thus be permitted.
It is interesting to note that at least some of these discussions are not specific to Yom Tov. The P’nei Yehoshua points out that the discussion, found in the Mishna on our daf of whether a person can say “fill up this jug for me” if it is a measuring utensil, may be an appropriate question for Shabbat as well as for Yom Tov, since it is not specifically related to an issue of food preparation. As such, he asks, why is this Mishna placed in Beitza and not in Massekhet?
Several answers are suggested in response to this question. The Bigdei Yom Tov, for example, argues that, given the leniencies permitted with regard to food preparation on Yom Tov, we could logically conclude that we should allow for these activities, as well. It is therefore essential for the Mishna to teach that weighing and measuring appear so much like forbidden business activities that we cannot permit them on Yom Tov, even for essential food preparation.