In my feeble attempt to answer this question, scaling up recipes and even following recipes to the exact amount may not always work due to numerous factors...

Factor One - Inconsistency of Recipe

The chef who wrote those recipes may not have used the precise amount of ingredients as per stated in the cook books. They usually just provide an estimated amount. Also, some chefs don't use precise measuring equipment. As such, they quantity of ingredients noted in the recipes may have fluctuated from what was actually used. These variations and minor errors can contribute to greater variances in taste when you scale recipes up.

Factor Two - Inconsistency of Ingredients

Can we say that one chicken will taste exactly the same as the other chicken - meaning they will have the same amount of sodium, fat, glucose, minerals and etc? Same goes for one tomato as compared to another tomato. Ingredients are not 100% the same and hence cannot give a 100% linear taste when scaling up. 

Factor Three - Random Physics, Chemistry and other Science Stuff

Let's use simple example like boiling soup. Imagine if you use a standard 3 litre pot to prepare 2 litres of soup. Now imagine you then use a bigger pot, like a 10 litre pot to boil 6 litres of soup. Would the water evaporate faster in a 3 litre pot or a 10 litre pot? Also, if your 3 litre pot made of the same steel as the 10 litre pot? Would the ingredients cook faster in a 3 litre pot or a 10 litre pot? Would it take 3 times as long to cook in a 10 litre pot? If it takes longer to cook, would this mean that there would be more evaporation of water leaving the soup more salty? Also, would prolonged boiling make the meat release more sodium and minerals into the soup, thus making it tastier? If it takes a shorter time to cook, this would leave the soup tasteless? All of this and much more can alter the the taste. Another note is 'when' you add salt to the soup. Adding salt at the start will bring it to boil faster and evaporation will commence faster...

Factor Four - People using the Recipe and the Ingredients

This one's easy. Some people are just not born to cook well :)

I suggest it may be because the surface area to volume ratio of larger cooking pots is lesser than for a smaller pot. For example, an 18cm diameter x 7cm deep pot will have a volume of around 1.78litres and a surface area in contact with the contents of about 650 square centimetres, giving a ratio of 365 square cm/litre. A pot 24cm diameter x 9cm has a volume of 4 litres and a surface area of 1130 cubic cm's giving a ratio of 283 square cm's/ litre. So my hypothesis is: "A more significant amount of flavouring remains stuck to the side of a small pot than for a large pot."

my family owns a business that produces mass quantities of spiced foods. the recipie that we use is actually highly subjective with respect to spices , because spices themselves are inherently variable by nature...the taste varies with age of the spice , storage condition , cooking conditions....now as to why spices usage drops soo much when u increase quantities, thats actually a straightforward answer, not as much of the spice actually decays during the cooking process , because the larger the amount of food u cook at once , generally the more efficiently its done, thats because its usually done at lower temperatures and for longer periods of times , thus the spices create the same interactions with your food as more would have done in less time with higher energy inputs...now with respect to salts , there is something the average person would not knw but , the finer the grain of the salt , the less u would actually taste it... thus courser grains are preferable ( atleast in my business)... im guessing there is an explanation in terms of solubility and so on, i knw from the textures of my food that when u scale up it takes longer for salts to dissolve in your foodstuff , thus it is possible for fragmented grains to exists in the mixture( just speculation though) ....another thing to consider is that when ur scaling up food cooking production , that you tend to have the change the process by which you cook the food.... and every good cook knws that process is everything, you can have the best eggs on the planet and still burn an omlet lol..hope ive answered ur q satisfactorily, i honestly cant go into more detail cuz thats all i knw for now