Bathrooms can not be that much - rationalise this for me

I have a small bathroom - large bath width by large bath length - currently has electric shower basin and toilet… whatever

Been quoted ‘ballpark’ £8k from one guy and £7-10 from another…. Can someone help me understand the rational as it can not be that much….. time effort etc.

Both commented about getting proper stuff, not Victoria plum etc, but even if we saying £1000 bath and taps and £1000 sink AND basin and £1000 shower (which is crazy) we talking £5000 labour?? How long would they be in there for? Am I paying like £500 a day labour?

What am I missing here?