I don't think anyone has talked about an 'outbreak' let alone a 'huge' one, of gastroenteritis, Lady T.
We're actually pointing to an endemic , unavoidable consequence of using formula. It is irrelevant whether the consequence comes direct from the product itself (it does) or if it comes from the way it is used (it does that, too), or if it comes from something(s) lacking in the formula (it does that, as well).
The risk of the consequences can be reduced by
i) care in the manufacture and production and packaging and storing and transporting - and we have laws to oversee that
ii) care in the way the equipment is handled - and we are well-informed of this in the UK, on the whole, and my own observation of parents is that they take good care to keep things clean
iii) care in the way the product is prepared - I think there is room for improvement here, but as time goes on, the confusion will be lessened. There are plenty of leaflets from many organisations (including NCT, including UNICEF, including WHO) that repeat the instructions clearly
But even with attention paid to all this, you are asking for the moon for all the risks of gastro to be reduced to zero. Maybe you have some other ideas on how we could get a bit closer to the moon?
(In any case, gastro is only one difference between bf and ff. It gets a lot of attention because it's reasonably easy to research and measure, and is fairly common)