I'm suspecting these companies are trying to use Data Caps to "Deter Piracy" without saying as much.
Unfortunately; the reality now is that these Data Caps do not just affect rampant pirates or people who download a lot of things. They are trying to justify an outdated policy that no longer works as intended; and hoping customers won't notice them taking a bit more profit off the top.
They've been more than caught now and the practice must stop or customers will get federal regulators involved