Shipping a gift to Scotland from US, why would they have to pay customs?

Stuff from the US to here seems to get hit more often than from anywhere else.

That said, I've had a $200 light dropped on my desk with no charges at all. Shipped from Elektrolumens with an honest Customs declaration on it.

I also had some software sent which had $1199.50 valuation on the declaration (Someone forgot where to put the decimal point and billed me that instead of $119.95. And then refunded it within an hour - and Fedexed a letter to me to apologise). No duty. But in the last 5 years I've stopped importing from the US if i can get it within the EU or from China.