Text is unlimited on most every type of account plan. Text uses data, but that data does not count towards the data allowance on plans with unlimited texting, to include Loyalty and Individual lines as well as More Everything lines.
Not only does texting not count against your data even if it did text messages use at most 160 bytes. You'd have to send and receive at least 6 million text messages a month to use 1 GB. There are only 2.6 million seconds in a month. You'd have to send and receive 6000 a month to exceed 1 MB which is nothing.
Even on MMS that max file size is 1.2 MB. So you'd have to send and receive at least 800 total per month to exceed 1 GB.
Don't mix up iMessages and SMS text messages. One uses data and has no relation to your text plan and is an Apple service. iMessages doesn't compress photos and uses data. The SMS/MMS/IMS uses you text pool and if you send MMS it is compressed to send and the data used isn't used against your data.
Blue = iMessages uses data bucket
Green = SMS/MMS/IMS uses text bucket
It's not false advertising.