[Ruling on what a child eats stealthily from people’s fruit]

Answer—and Allah is the One who grants success: What is required in such a case is that the legally responsible person consider the owners from whom he took:
1. If he knows a person to be magnanimous, easy-going, such that—were he to know—he would pardon of his own good will, then actual, explicit pardon is not required.
2. If he knows a person to be tight-fisted and not good-natured in this regard, then he must seek pardon; if the owner pardons, fine; otherwise, the now-responsible person should reach a settlement with him for an amount they both agree upon.
3. If he is unsure to which of the two categories a person belongs, then he must seek pardon, and so forth.
Yes: it may be said: If the local custom runs in favor of overlooking such past matters, then seeking pardon is not required. This is what is known in our land: the owner does not demand compensation from the children’s guardians nor hold them liable; if an owner is particular, he complains to the guardians so they prevent and discipline the children; even were the guardians to offer payment, he would refuse it out of pride. If matters are thus, the now-responsible person is not obliged to seek pardon nor to pay for what he took in childhood.
Yes: It is narrated—as in the marginalia on al-Baḥr al-Zakhkhār—that the Prophet (May Allah bless him and his family and grant them peace) said: “If you come upon a garden wall not enclosed by a building, call its owner three times; if he answers you, [seek his leave]; otherwise, eat—so long as you do not cause damage.” This ḥadīth lends some support to what we have said; nevertheless, it remains obligatory to avoid eating people’s wealth, their fruit, and the yield of their orchards, given the well-known Islamic prohibition against consuming people’s wealth: “O believers! Do not consume one another’s wealth unjustly, but only [in lawful] business by mutual consent …” [An-Nisāʾ:29]. And in the famous ḥadīth: “The property of a Muslim is not lawful except with his willing consent."
Yes: Eating fruit without the owners’ permission is permissible when their custom runs that way—such as with eating from the ʿilb (jujube) trees without their owners’ leave—or when the matter is very slight, as is the case in many of the Bedouin areas of Ṣaʿdah.

Source: Min Thimār al-ʿIlm wa al-Ḥikmah vol.2