Lexus labour rates are up to £120 per hour, but this isn't just about the amount paid to a mechanic it is also the additional overheads of the dealership that need to be covered.
Parts bare no resemblance to the manufacturing costs, be that Toyota, Lexus or any other manufacturer, however additional markup is placed on Lexus parts compared to Toyota.
Warranty is directly related to the market. Toyota GB could easily put on a 5 year warranty onto their Lexus vehicles but they choose not to because the competition they compete against in this country doesn't and they would probably have to raise vehicle list prices to cover the additional costs anyway.
In other countries, again Lexus compete against their local competition and what the public in that location is willing to accept. There is also economies of scale at work here - the US sells more Lexus in 2 weeks compared to 12 months of sales in the UK.
You can be upset/disappointed/annoyed/angry about it but that is the reality. Factor it into the overall ownership costs of the vehicle to make a decision of whether it is right for you or not.