What's normal isn't the problem. The problem is if said Walmart doesn't have a way for a new customer to call up and say "our staff is only ever authorized to order 1 trailer a day; if they ask for more, don't fullfil until you have written confirmation that we authorise the amount, or we won't pay".

Plenty of companies operate like that, and e.g. require purchase order ids and accompanying maximum spends issued for any expense over X, where X can be very low. I've worked for companies where it was 0 - every expense, no matter how low, needed prior approval from the CEO or finance director. Not just tiny companies either - one of the strictest such policies I've dealt with was with a company of more than a hundred employees.