I have multiple theories, not mutually exclusive. One 1. They don't know. I'm not being clever either, Brexit has just straight up shown that a lot of politicians, like the public, don't actually know anything about the EU or how it works. That's not surprising for the public, I only know because of my degree, but for the government it's more than a little concerning. (Edit 1 below) Two 2. Politicians have a basic refusal to ever tell the public they're straight up wrong. If you ever watch Question Time, as an example, you can have an objectively idiotic statement from someone and an MP will still give a washy roundabout answer. Votes are all, and politicians don't want to risk negative press by telling people they're factually wrong about something. Trust me, I find that infuriating too. Three 3. Brexit is too far gone. May wanted to remain, and now she's banging the drum to respect the referendum result harder than anyone else in Parliament, even when there's increasing support for another vote or just to extend the deadline. There's such a strong sense of...I can't find the word. Entitlement is wrong but it's the closest. Brexit has to happen basically. So telling people all they think about the EU is wrong comes across as undermining brexit. For the Tories at least, given that this happened to prevent them losing voters to UKIP, they can't really afford to annoy that crowd by, again, telling them they're wrong. For Labour, well, Corbyn doesn't like the EU so why would he. The Libdems and the Greens are saying some of this stuff, but don't get any wide coverage.(Edit 2 below) Four 4. The media is pretty fully behind brexit. A lot of the misconceptions exist because the media has stoked them. Unsurprising, given all the popular ones are owned by one dude who would do well out of not having the EU introduce their tax evasion laws, among a few other things. This is serious enough the EU Commission actually has a website dedicated to all the times the UK media has outright lied about something the EU has done for the sake of causing outrage. "bendy bananas" being the most well known example, but here's the full list. European Commission in the UK - European Commission Five 5. People wouldn't listen. I'm going to sound very elitist and egotistical here, but I am a firm believer that the more people you talk to, the more the IQ drops. And frankly, if brexit has revealed one singular fact to me, its that the average person has zero interest in objective learning. I can not tell you how long I've spent the last two years doing my best to debunk myths about the EU that are widely believed. I can tell you that less than a handful of people have read what I've said and then changed their mind. Brexit is a heart issue. People truly, deeply believe what they're voting for, and something as inconvenient as facts simply does not matter. I can tell you in a paragraph why the EU is not a dictatorship (and arguably is actually more democratic than the UK system) and I have had it roundly ignored and the same debate continued for days after on plenty of occasions. Now that doesn't excuse the government from not at least trying to do that, but I do think it would be an exercise in futility. (Edit 3 below) Edits 1) An add here. In a debate about the Irish backstop a Conservative MP basically said that Ireland should learn its place and why is it even getting involved in the discussion. About their own border. While being a sovereign country. Like brexit wasn't largely about the UK wanting secure borders, and then a year of people shouting at Ireland and the EU for wanting the same. That's one example of the kind of people we have in Parliament and the level of information some of them have. 2) The simplest way of showing this actually is, again with the Irish border, as it stands there's basically two choices in reality: A hard border, or we agree have a customs union with the EU. Those are the only two actual choices. Neither of those is palatable to people who voted leave however, so the government won't confront people with that reality because it would be unpopular. 3) WTO Rules is another example. Hard brexit people parrot that at me now they've seen it said somewhere before, and flat out ignore being informed that WTO rules very much don't solve the Irish border question. And on the border in general, a lot of people seem to believe we can just unilaterally decide "well we say no and we're walking away" like that would solve the issue. I think the average person just can't grasp international relations and the fact that the UK exists in a community of other countries that we can't just remove ourselves from.