Median income in the US is higher than Poland (which just means you might expect people to spend more on similar things), and cell phone company marketing has been very successful selling higher cost plans (which helps them avoid competing on price).
The last 12 months has seen more price competition ($40 a month on T Mobile is the data equivalent of your plan, with unlimited voice (that's the no contract plan)).
An example of how successful the marketing has been, people regularly talk about the subsidy they get from the phone company to buy their phone. It's really a contract where they end up paying more than the price of the phone (plus interest), but it still gets called a subsidy.
The last 12 months has seen more price competition ($40 a month on T Mobile is the data equivalent of your plan, with unlimited voice (that's the no contract plan)).
An example of how successful the marketing has been, people regularly talk about the subsidy they get from the phone company to buy their phone. It's really a contract where they end up paying more than the price of the phone (plus interest), but it still gets called a subsidy.