The inventory situation you just described is not limited to tool trucks!
EVERY business that sells inventory items has to make those decisions.
For instance, let's look at Summit Racing: You call, you place your order, they take your credit card number, a couple days later your parts show up at the door.
Let's look at any number of other smaller companies: You call, you place your order, the operator says half the items are back-ordered and they should get them in two to four weeks, they take your credit card and you get half your stuff later that week, the rest dribbles in over the next month.
Or, more likely, you say "screw that. I saved up the money, I have a time I want to install them, I want my parts, I don't want to pay for shipping on three packages when it'd be just one if you had them all in stock; I'll call someone who has them in stock."
Good businesses realize they are losing sales by not having inventory in-stock, ready to ship.
Poor businesses think inventory is "money that's *******," and customers will gladly wait for the back-ordered parts to ship when the company gets them in... which is usually when enough other customers order the same part, so they are buying several of one item from their supplier.
I've seen countless orders canceled because someone wanted to buy an intake, carb, air cleaner, hardware kit and gaskets, but one of the items wasn't in stock, so the customer canceled it all and bought elsewhere.
Short-sighted on the part of the business owners.
-Brad