Sealed from the inside, so longer service life, potentially - loads longer, as grime is what kills bike bearings. Forces alignment regardless of what bottom bracket shell machining. Replacable bearings.
I mean - in the world of $2000 groupsets, 280 euros for a BB that is built to industrial standards seems about right. Besides - it is a custom made, short production run item and the price reflects that.
Chinese can churn out those at $20 in jiffy, but they probably don't care.