The situation for new builds / speculative construction which are then placed on the market, versus 'having a house built to your specifications', might be some of the difference. Or you (that is, not you or I, but "people") might select a "style" of bathroom or use a particular interior designer whom you trust to make appropriate decisions.

If you're not getting an incredibly detailed itemised bill, you might find it tough to spot ~1K extra in 'bathroom furniture and installations'