At a coin-operated parking lot I was charged much more than I had expected and I don’t understand why.

The rates for coin-operated parking lots are often based on location, time of day, and a host of other conditions. The rate may depend on whether it is a weekday or holiday, or daytime or nighttime, for example. A special rate may also apply to the year-end/New Year holiday or during an event being held nearby. Rates and terms of use must be displayed according to rules set by an industry organization, but sometimes the sign can be difficult to read or it can be set up only at the back of the parking lot. Basically, you must adhere to the terms displayed, but if there is a reason you do not understand or accept, contact the company that runs the parking lot and talk to them.