NN doesn't prevent a carrier from offering a plan with Unlimited* data where the asterisk means "up to 25GB at maximum speed, lowered to 128/64 Kbps after exceeding the limit, until the end of billing period".
It would prevent the carrier from not counting certain traffic in the data usage or not limiting the speed of some traffic after the data limit is reached.
NN doesn't prevent a carrier from offering a plan with Unlimited* data where the asterisk means "up to 25GB at maximum speed, lowered to 128/64 Kbps after exceeding the limit, until the end of billing period".
It would prevent the carrier from not counting certain traffic in the data usage or not limiting the speed of some traffic after the data limit is reached.