Because the majority isn't always right. Human nature naturally forms groups, but the desire can be stronger than the discrimination required in choosing those groups. They are secondarily affected by peer and group pressure and again this easily overrides many aspects of logic and commonsense, until after the event when many people look back on their decision and regret it bitterly. Norway are the example of where the sense has remained greater than the outside pressure and as a result few if any of the associated problems we are suffering as net contributors, let alone incredibly restricting rules will affect them while proving you can still enjoy all the supposed benefits from the outside. Not that anyone in our own government would dare to admit it.