In my city (I live near an airport) there was a case when a cab driver got 18 months in prison since he was charging tourists that did not know better unreasonable cab faires. The tourists payed fully aware of the costs but then understood there where not reasonably priced and filed a police report and the scammer was sent to jail.

Tricking someone to buy something for an unreasonable price IS illegal regardless if the the buyer has seen the price and accidently hits an ok button. I am 100% sure a real life equivalent the buyer would win the case in court. It is as you say extrememly easy to understand that the intent is to trick someone into buying and that is what is illegal regardless if it is by lying about the product or by taking advantage of a poorly implemented system that makes it easy to accidently purchase an item for unreasonable prices. I think you have a misunderstanding of the law here.

Fun fact, in my country its even not allowed to buy a thing for LESS than a reasonably price for an item, because it is then argued that you should understand that something is fishy with the deal (ie. its probably stolen).