Mass-produced bread is loaded with extra fat and additives, to reduce the fermentation time.
It’s not really that different. Fat’s added to lots of traditional breads in similar (around the 1-2% mark) or significantly greater proportions to chorleywood (and the like) processed loaves. It uses a fair bit of yeast – but again, plenty of traditional loaves are heavily yeasted – about double what you’d reckon for a standard home baked white loaf.
Sure there are some emulsifiers in a lot of loaves and then there’s typically something like 1% “improvers” of which ascorbic acid’s the main other ingredient – again, not uncommon amongst more traditional bakers and the rest is largely enzymes which increase proving speed these days but it’s not in quantities that you could reasonably call “loaded”.
The main difference with mass produced loaves isn’t the ingredients but that they effectively have air whipped into them to avoid having to be left to rise.
As it happens I’d wager there’s more fat, salt and sugar in the homemade Vollkornbrot that I just had for lunch than in your average cheap white bread.