> I garuntee a box mix will make a much better cake than "from scratch" unless you are very experienced.
That is simply untrue. It does not take an experienced baker to make a better cake than a boxed cake mix. The fact that you can avoid the other weird ingredients (which are probably not terrible at small scale) is just the icing on the cake.
As others have said elsewhere, some of the ingredients involved are not easily available/cost-efficient for the home baker. This means it's more than possible that you will get an objectively better cake from a mix, e.g. from blind tasting.
This does depend on the type of cake you're baking and your expectations of 'better' though.
Would love to see such a video. I could imagine using certain box mixes for certain specific purposes, but for most of their baking? I cannot imagine this being claimed by even a casual cook/baker.
> some of the ingredients involved are not easily available/cost-efficient for the home baker
Sure, but some of these are also only necessary because the box has to have a very long shelf life. If you buy your staple ingredients every month or two, you don't need stabilizers and such.
Maybe expectations for cake in the USA are different from the rest of the world, like it is for sliced bread (soft as a pillow). I seriously doubt bakeries in most of europe use cake mixes, or at least nothing with a similar laundry list of chemicals.
Blind testing is missing the point - you're not trying to emulate some perfect standard. The little imperfections and variances in the result are the value.