Why is UPS allowed to hold my package hostage?

How can a company tell you a price for shipping, not tell you about their fee, then charge as much as they want in so-called brokerage fees to the receiver? Do they not have to be honest about that charge upfront? Small print saying their might be taxes and other charges is not being honest at all when the fee is almost as much as the cost of the package. Regular mail brokerage fee is a set cost of $5.00, but UPS can charge hundreds all without the shipper knowing. Then the package gets to the receiver and they won't sign it over without a payment that they made up. How is that not illegal?