I think that the analogy is reasonable, mainly because both examples are the type of debts that can be serviced (i.e. repaid) anytime (unless your utilities needs to be pre-paid before you can use it, which in case it breaks down because it becomes a bought thing, not a borrowed thing). There are recommended schedules to pay them, as well as a hard deadline, but you can usually pay them early (and sometimes those early payments can be rewarded, for example by reduced interests).

Your example mainly deals with futures (a type of financial instrument), mainly because you have agreed to pay within a tight schedule, which does not allow you to service them too early nor too late. Also, you forgot that money was invented to be widely fungible (okay, you can argue if this is true in this age but I argue it's still largely is) meaning that it can be (relatively speaking) easier to convert to corn, stocks, or generators (for example), which is different from corn which is only usable to a subset of people, meaning that you can only deal with those people which needs or wants corn (for example, you cannot easily get generators with corn).