Exactly, here the users that are using less than average bandwidth are subsidizing others, so the pricing can't be considered fair or economically efficient. So this is just a way for ISP's to generate more profits compared to flat rate.
Despite pure flat rate never being economically efficient, it's usually very profitable for ISP's because core network capacity (at least used to be) 1/100th of the price of access capacity. When the access part is already installed and paid for, the operators don't have any other reason for bandwidth caps than greed. However, in expensive bottleneck links like radio this is different than in wired access.