In the west, sure. But that can't be generalized to all over the world. In some developing countries the internet connection costs of an operator can be very s

In the west, sure. But that can't be generalized to all over the world. In some developing countries the internet connection costs of an operator can be very significant. High enough that it's been profitable to deploy expensive caches even for non-HTTP protocols, which account for a very small proportion of traffic. In the most extreme cases it's not just that the connectivity is expensive, it's that there's an absolute hard cap on bandwidth for a whole country, which is rationed among all the operators. No amount of money could buy a bigger portion in a sensible amount of time.