There is a very simple solution, do not look at the television screen.
The system works by taking a picture, assessing our age and sex and showing what they consider an advert appropriate to our age and sex, it then registers how long we look at it. If we do not look at it at all the system will feed back to the advertiser that their campaign was a complete failure.
If I am forced to use a Tesco petrol station I will either pay at pump or, if that is not possible, read my Kindle while I am in the queue, making both assessment of age, if not sex, difficult and, I will clearly not be watching the screen.