Why is always the most expensive wine corked?

I visited customers last week in England and tasted some fantastic wines.
Decisions now have to be made for pre Christmas orders, so it is an important time.
With one wine merchant I set up a tasting of three different vintages of Chateau Haut Maurac, Cru Bourgeois Medoc. It was really interesting to see the 2003 next to the 2004 and then the 2005. These wines will sell at the important price level between £12-£15.
To review:
2003 Ch. Haut Maurac....very smooth evolved, but very well balanced style. Good depth of spicy blackcurrant and creamy oak harmony. Decanter selected this for Septembers Wine of the Month.
2004 Ch. Haut Maurac....more earthy and classic 'old fashioned' style of Bordeaux...similar to Ch. Cissac. No faults just old style and fleshy rather than soft fruits.
2005 Ch. Haut Maurac....very interesting to try again having tasted several times. Still showing exceptionally well. Absolute perfect balance with super intense deep dark mature fruits and evident oak showing its current youthfulness....this will age for another 5-7 years at least.
Then we poured the 'piece de resistance' a Saint Emilion Grand Cru from the 2005 vintage that we were both really looking forward to...it would potentially retail at £27....IT WAS CORKED.
I know that much has been written about natural corks versus plastic corks as well as alternative screw cap closures....but this was really frustrating. Nobody really knows the true statistics for the percentage of corked wines. Maybe it is 1%, but it could be as much as 5%. What other industry would tolerate this level of wastage/spoilage?? My frustrations are financial! I traveled a long way to visit a good customer and allocated a specific time (9am!) to taste an important range of wines. We were both deflated and annoyed that the sample was corked but we both realized that this is an ongoing industry issue. The wine world evolves and has innovative periods...it has certainly evolved from the time when a rag was stuffed into an urn!...but we still need to do something about cork taint, TCA and corked wines.
However the tasting finished on a high note when we tasted the stunning Mas Amiel Mini Maury NV. (in the picture)This is a rich 100% Grenache wine with a blend of red fruits and a hint of mature dark fruits. If anyone likes chocolate! This is THE wine. A must for the Christmas table this year.