Ray, whilst I am not happy at the thought of paying more than I have to for anything, I have to agree that some form of qualification might help. However, how on Earth would you police it? How do you show that your A quality lens is inferior (as it sometimes still might turn out to be) to the B quality version, and get your refund?
I would rather bite the bullet and pay more on the understanding that any lens I bought from Nikon was going to be top-grade and reliable - a staggered array of standards might just become a further cop-out for the makers, though I do remember that Nikon played with that idea with its E lenses. Final inspection and quality control is the responsibility of the maker, not the buyer; why should we have to buy inconvenience along with the glass?
Attention has been drawn to competition between brands as being a sort of alternative quality control of its own - I don't think so. It seems to me that the reverse holds true: all makers are in the same boat and happy to paddle along together at the lowest possible cost to themselves. In a sense, the internet has actually helped them in a sort of perverse manner, because they know perfectly well that the forums are full of moans and groans about all of them, and few are likely to swap brands, lose a fortune in gear, simply to swap over from one company that they mistrust to another whose products are just as slated by other owners.
Come to think of it, Leica seems to be the only firm whose customers seem happy with the lenses it produces. I can't think those people are all stupid.
Policing should not be a problem. We have the internet.
This is also why I suggested that any company specialising in the MTF testing of lenses straight from the factory floor, should have an association with, and endorsement by, the manufacturer, otherwise it's would be too easy for a disreputable private lens-testing company, experiencing a shortage of Grade A lenses of a particular model, to substitute grade C or D lenses which were in plentiful supply, and use fake MTF charts.
The problem at present seems to be that the QC tolerance range for many popular lenses is from Grade A to Grade E. If you have the time and opportunity to spend many hours and even days testing and comparing a number of different copies of a particular model of lens from perhaps a number of different suppliers, in order to cherry pick a Grade A copy, you might consider your time and effort well spent, if you eventually succeed.
However, if you fail to find a Grade A copy after a lot of effort, how do you know when to stop? This happened to me with the Canon EF-S 10-22mm. I tested 3 different copies from 3 different suppliers. Each retailer I visited had only one copy of the lens in stock at the time; one in Australia; one in Singapore, and one in Kuala Lumpur. I took photos in each shop, comparing the quality on my laptop with identical shots from my Sigma 15-30 at 15mm.
The third lens I tested in KL appeared to be the best and the closest in sharpness to my Sigma, but still not quite as sharp as the Sigma. I was very undecided, but ended up buying it because the price was so good and the sales assistant was so helpful and so attractive.
I wish I hadn't. I rarely use the lens because it's really not up to scratch. I recently compared a few shots using the 15mp 50D with the EF-S10-22, and the 12mp D700 with the Nikkor 14-24. Despite the higher pixel count of the 50D, the D700 shots with Nikkor 14-24 were vastly superior.
With my idea of including real MTF charts specific to each lens sold, the customer would know exactly what he's buying (if he takes the trouble to inform himself) and the manufacturer would know exacly how much the customer is prepared to pay for a premium product, and might adjust their own QC practices accordingly.
We'd all benefit from such a process.
It's all very well saying, why not just buy an expensive lens like a Leica or Zeiss manufactured with more stringent QC practices. Do they have the type, the fitting, the focal length, the IS or VR that one desires? Not in my case. Two lenses I use a lot are the Canons 24-105 and 100-400 zooms. They both have IS and autofocus, and both complement each other in focal length. There are simply no other lenses available with the same features and a Canon fit.