Yes, the difference between ta and at is not all that great, but it is there. Bad copy? I did a print screen, which is all digital, there shouldn't be any mistakes added like if I had printed and scanned it or anything. Photoshop did add some blending when I increased the size, but that's done according to a very exacting mathematical equation and doesn't change the beginning and end of the characters horizontally. From the pic it is obvious that there is a clear difference between the pair. Don't trust it with smudging? Here it is again without that:
And look, the top pixel of the a tail is clearly underneath the cross bar of the t.
The a and t letters don't any have overhang like f does.
So if it's not technically kerning, it's still something, whatever the technical name of it is, that's making those letter pairs different sizes.