They don't...and I wouldn't be: cheaper lenses wouldn't stand up to the punishment I mete out, not do they come with the wider apertures I demand.
Also, I
have done tests myself to confirm to my own satisfaction that all my lenses are good edge-to-edge at all apertures compared to manufacturers' claims: it's the first thing I do with a new lens when I buy it (with issued kit I don't bother).
The properties of the 17-35; 24-70; 70-200; 50-mil and 85-mil are already well enough documented anyway.
I just
can't be arsed to do it all again for your benefit and besides: hand-held living-room tests ultimately prove nothing - too many variables: leave that up to the Lab-Geeks and bench-tests in controlled environments.
All I was doing here was trying to demonstrate that zooms
can be as good as primes. I've done that...
and you bloody-well agreed...
...you Bloomin' ****-stirrer...