Would you say that? There is a crucial difference (between a paid and an unpaid watcher), viz.: Since a paid watcher both derives benefit and gives benefit, and a hirer derives benefit and gives benefit, then the second is to be compared to the first, who swears (for exemption from liability) for accident and pays for theft and loss, and this is not to be refuted by an unpaid watcher, who gives benefit but does not derive it. This is the intent of "If it were hired, it came by its hire" (i.e., it is to be compared to a hired watcher and not to an unhired one.)