Bit too simplistic an explanation in my view. It overlooks the fact that the coal and steel community formed by the Treaty of Rome was signed up to by countries in Europe because they’d spent centuries going to war with each other. Britain as a more remote island on the continent was more removed. Yes we’d gone to war in Crimea, the Peninsular wars etc in the past 100-150 years but far more few and far between than on the rest the continent plus France and yes Germany had suffered far more in terms of casualties and economic hardship in the Second World War than us. Therefore economic cooperation was seen as a way of making sure it never happened again, with Britain which was going through a decline in its global influence it was more navel gazing and although MacMillan wanted us to join…there was no great enthusiasm in the country as a whole.
Also you simply can’t ignore a difference in culture as a long standing reason for indifference to the European Union. We have far more in common for obvious reasons with the Anglosphere countries
Do I think that it was never considered a big issue for most people other than a few years prior to 2016 ? Yeah that’s self evident in polling. But what’s equally self evident is that the anti EU message that people like Farage promoted only worked because people were receptive to it…they were fed up with things economically and with immigration. When James Goldsmith and his Referendum party had tried to gin up support for leaving twenty years previous he’d got nowhere.
So basically the EU has never been particularly loved by people in this country to begin with. And politicians of both parties played on this, the Lisbon Treaty was signed behind closed doors by Brown (betraying the fact that privately politicians were more pro EU than they claimed to be in public)
None of this particularly matters to me, the only thing I was against was the single currency…and if people understand anything about what happened with Greece, they would be too.