CornishKK - the Department of Health/NHS do publish information on formula feeding - for example this leaflet. The information is out there.
StrictlyBoogying - no, the fact that you don't change your car insurance every day is precisely the issue. At some point, you "chose" a brand, and - by and large - stuck with it.
Market/consumer research shows that consumers - on the whole - then remain pretty loyal to "their" brand, and construct narratives about why their choice was "just right" for them, how it perfectly encapsulates what they want from a product, etc.
Except its mostly all nonsense: we like to feel that we've "chosen" a product really well, that it suits us "as individuals", etc. Capitalism feeds the idea that we - as individuals - can choose and buy products which are somehow individually tailored for us. But they're not. And formula is the same, in many respects.
Some babies will get on with one formula, others won't. It's not down to some special "choice", but arbitrary factors which can't be predetermined by "choice". When a person lands on a formula that works for their DC, it's not because they've "chosen well", IYSWIM.
What if you chose Aptamil, based on loads of apparently sound information about it, but then it gave your DC constipation? Would you persevere because it was the "best choice"?