“(1) the people were not told that the government would act on the outcome (it was presented as an opinion poll)”
I beg your pardon but you need to read this leaflet, jayne (which was sent to every household in the UK:
https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/515068/why-the-government-believes-that-voting-to-remain-in-the-european-union-is-the-best-decision-for-the-uk.pdf
To save you the bother, on page 14 (of 16) it says this:
“This is your decision. The Government will implement what you decide.”
There was nothing that suggested it was an “opinion poll” and Mr Cameron (whom you may remember was the Prime Minister at the time) repeated his assurance on the telly.
“(2) the people did not know the terms on which we would leave, if we did.”
It was made quite clear (in the same leaflet and copiously in the press and on the radio and TV, what leaving would mean. It meant all the things that the government is now trying to avoid.
“The backstop is the natural consequence of both sides wanting to honour the Good Friday Agreement. People who call it "unnecessary" are therefore simply and demonstrably wrong.”
We’ve done this before, Jim and still there is no satisfactory answer forthcoming. The Good Friday Agreement is nothing to do with the EU so by “both sides” I assume you mean the UK and Ireland. Both have stated categorically that they will not implement a hard border in Ireland whatever the terms are under which the UK leaves the EU. The EU has also stated that it will not do so (though since they don’t have the authority for such action their assurance seems somewhat superfluous). So, nobody is going to impose a hard border but measures must be provided to ensure that one is not implemented. Quite how people who call it unnecessary are “therefore simply and demonstrably wrong” is hard to fathom. If anybody told me I was wrong to suggest you don’t need a solution to a problem that does not exist I’d question their logic.