Adding a fee when an order contains a backordered product?

Why would you add a fee for a back order?

Now, I don't know what your business is but this is something I don't understand if it's just an inventory product based e commerce business.

Is it some special item where you're just like "Hey, if you really want this, I gotta charge you extra because I now need to make it or order it specially just for you", then sure. Maybe it's a special item, but I don't personally know.

A back order is beneficial to the e commerce company and disadvantageous to the customer.

If you can't keep your inventory levels sufficient, but allow back orders, you shouldn't add a fee for it [if it's not a special item].

If your issue is holding stock [for purchases currently in stock] because you're shipping everything out in one package [if the purchase includes a back ordered product] (due to shipping costs at checkout) and must wait for inventory to come in to fulfill the order in one complete package, you should be looking for a plugin that allows you to separate orders at checkout or, you can simply charge shipping separately [per product] (add to checkout for backorder items), which woocommerce allows.

/r/woocommerce Thread