Yup, but it's easier for some foods than for others. You can easily take two eggs, cook them exactly identically, and try them both side-by-side. Similarly for wines, which don't even require cooking. It's a bit harder with, say, a chicken for roasting. Even if you have an oven that'll take two chickens and don't have a spouse who'll object to roasting two when you only need one, it's far from trivial to avoid (say) overcooking one a little and undercooking the other a little, and that difference could easily swamp the subtler one you're looking for.

I'm not disagreeing that the question really ought to be answered empirically, but I'm not convinced it's so easy to do in practice.

Of course, what's hard for me with my small family and ordinary-sized kitchen may be easier for (e.g.) a restaurant or a consumer advocacy organization or whatever. I had a look on the web to see if anyone else has done this sort of testing. I found a small number of small-scale tests with inconclusive results. Enough to rule out "organically produced food is almost always much better", but I never believed that in the first place. (And enough to reduce my confidence in "organically produced food is a bit better on average", but not very much because of the low power of the tests.)