Totally agree with LaurieMarlow: "From a marketing POV, it is a great campaign. People like certainty & clear goals - 'eat loads of fruit & veg' is much too vague - wouldn't have made anything like the impact."
The NHS are trying to convey a simple message to millions of people, some of whom will already have excellent nutritional awareness (hence '5 a day' seeming patronising) and some of whom will have zero. Like Margiemar, I know people who eat one portion of veg a day and think that's totally sufficient. The NHS gets a lot of stick, but it has to be pragmatic. People often distort messages to suit their own habits, or just ignore them entirely if they seem too harsh or convoluted.
'Eat 7 portions of veg a day' --> never going to happen, why bother at all?
'Eat 3 portions of veg a day' --> so probably 1 would do.
'Potatoes count towards your portions if...' --> chips are fine, then.
'... as part of a balanced diet...' --> nearly everyone thinks they eat a balanced diet, on the whole. It's like having good taste and a great sense of humour.
'... in moderation...' --> hopelessly relative measure, generally received as 'consume nine-tenths of your normal portion and congratulate yourself on such forbearance'.
And if the message isn't 100% consistent, then fuck it all. They're always making shit up, just to annoy me! Last decade, it was 'eat 8 portions of veg', and now it's 'eat 4'. The information is therefore completely useless.
It's really easy to pick apart and deride almost every piece of advice the NHS gives, but considering the psychology of trying to mass-market nutritional advice and actually affect people's behaviour, they have an almost impossible job.