Virgil, I didn't say you couldn't do what you are suggesting but the actual practicality of it is limited and probability is unlikely. Summoning a force 12 spirit while supposedly possible for a starting magician, is very unlikely. The disparity in dice pools and edge means the spirit will most likely win. This will result in drain that is lethal, all so the company can move something quicker. The margin on the product needs to be such that it is worth chewing through a magician every time. Not likely.
As for executive jets, all the ones I've seen are body 17 or higher which means a spirit of force 8 or higher. Once more, while a magician can theoretically call and bind these kinds of spirits, it sure isn't an everyday thing. This also means the mage in question is quite powerful (high magic and skill) to reliably call these kind of spirits. Such an individual is unlikely to be employed moving cargo about, especially with a risk of death for doing so.
Player-Characters are of course an exception but your initial example used wage mages who are unlikely to have a magic of 6. Like I said, theoretically possible but not very likely outside an IE (Immortal Elf) or GD (Great Dragon) and they aren't sitting around moving cargo for anyone.
Edit: Recharge spell can be found in WAR! (pg 178)