My son works at a store that offers home delivery for a fee that is paid as part of the order. My son is also the delivery person. A neighbor would like to place an order with the store, but has asked my son if he wouldn’t mind bringing it home with him after he gets off work to avoid the delivery charge, whereupon the neighbor would pick it up from our home. This feels wrong ethically, but I’d like to hear what halacha says about it.

It is not a black or white situation, especially because your son would be bringing it home for your neighbor after he gets off work. The ideal thing to do, is ask the store owner for his permission. Most store owners wouldn’t mind, as long as they get the sale.