Can be true. Don't worry about this, I think it is similar to an importdealer for example. They can buy without permission from a higher chief for 50.000,-. From 50.000 to 100.000 the importdealer needs permission from his chief and above 100.000,- he needs permission and a sign from his director.
It's normal in bussines world, because there is an obligation to have this in your statute (it is in NL for sure). In practice it is like nothing. Just sending a mail or the invoice to your boss and when he mails back: yes. You can do the buy. It is an assurance that your employees will not do things outside the box, were he is not for appointed. Because if the employee exceed the rules he is responsible for damage.