I think every time I enter the European Union as a citizen (crossing the border in Denmark, Germany, the UK, France, the Netherlands or Spain) I've either not interacted with anyone (electronic border gate), or said nothing more than "hello" and "thank you".
Speaking to a customs official is very rare, I've only had that happen once.
Do most Americans get questioned at their own border? I do, but I'd assumed that was only for "aliens".