If I go to the gym and drop 100kg on myself then it is my fault for not understanding the risks, where it is reasonable to do so.
It is reasonable to expect you as a customer of the internet service to understand the service you are using and the costs involved. It really falls on no one elses shoulders.
I do agree that it tends to be over priced and the pricing structure is often confusing but I still think it's within the grasp of most to understand it.
It's pretty much like not giving you the car speedomoter, and then the city places speed trap cameras all over the city and then after a month, you get a bill for $200 because you went over 4 times.
This business make money first mentality is pretty bonkers.
The internet provider offers a service with certain penalties that are typically made clear enough if you read the contract. It is up to you, through whatever means you have available, to not use it in a way that gets you excess charges.
I like your speed trap analogy but I still don't think it is the ISP at fault. If you can't afford the overage and your phone has no metering then there are plans and pre paid plans available to suit that need. You are still the one signing up to the service and using it, you don't have to if you think the situation is unfair.
None the less, it is definitely a balance of transparency and I think it is fair to ask for app vendors to properly optimoze and advertise the data usage of their apps in some way.
People can understand it, but they usually don't habitually check it, resulting in surprise bills.
Some angry support tickets might be warranted though!
Last summer I was playing a fun little game on my iPhone and kept causing problems for other people on the same Wi-Fi network just me. It turned out that when you dismissed a video ad is soon as possible to skip it, it seemed to keep downloading the ad anyway. And then maybe some more. I don't know, but it was a huge data hog on Wi-Fi.
If that happened on cellular (I didn't play much while out and about, and it may have changed its behavior on cell) it could've easily racked up a huge bill. And that would be the developers fault.
In the two weeks I've been playing Pokémon go my iPhone says I've used 150 MB of data. I've been looking at it a lot as I drive around (whenever I stop in a parking lot), and I often leave it running while driving (to get those fake steps when I'm going slow enough) and it hasn't done much so I don't think the game is missbehaving. Given that it seems to have to constantly reload landmarks in areas I frequent some cashing might be a good idea, but it's not too horrendous.
I can definitely see regulators being concerned about this kind of predatory pricing. Carriers should price data close to what it costs them to offer it, not at outrageously high prices to milk as much money as possible out of their customers before they realize what they're spending.