I just checked in in Word and I see that the difference between at and ta is really very small. I think the apparent difference in your picture is just a result of bad copy. In any case the fundamental assertion that difference between, say fo and of (which is easily observable) is due to kerning is an incorrect use of terminology. This is not due to kerning - this is just because f has right overhang, which not the same as kerning.
The assertion that Times New Roman is "kerned automatically" is incorrect. See my explanation in the posts above
Look, this is a huge deal and let us be extra careful.
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.