The price should be whatever it costs you when including all cost factors¹. A competitive market is an attempt at a system (no central control) to approach that lower bound value. It's really hard to incorporate the million dependencies in a true cost price, so people are instead free to set a price and consumers are free to choose a vendor that's cheaper, and so there's competition. Markets are said to not be working well (lack of competition, usually) if the price of a good or service does not remotely approach the cost price

Bribes are usually to people in power because otherwise you'd just go with the non-corrupt option. That's not a functioning market. I wouldn't say that this type of monopoly is an attempt at determining the fair price for transporting an item of a given mass and dimensions

¹ this really includes everything: to be able to walk across the street and deliver packages, you needed to eat the night before; you needed to learn to read; you need to put money to the side for when you're of age; etc.