I agree to a certain extent. People are always going to have different political values and they are always going to spin what they agree with to look better and what they don't look worse.
I totally agree, you cannot quantify all of the benefits and pitfalls of such a complex system like the EU but there is a growing a feeling of dissatisfaction with the EU growing within member states and they need to be able show the person on the street the benefits of being the EU. Part of the reason the leave campaign was so successful was because they could show people figures, granted a lot of them were exaggerated or even outright lies, but remain had nothing to counter them with.
Unfortunately there is no easy solution.
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Not really. If Trump turns out to be a disaster the US electorate can correct that mistake in four years time. If Brexit is a disaster we are stuck with it.