I don't know the exact reasons why, but food made in large batches tends to be less tasty than food made in smaller batches at home. if the food is made in large batches and it's not fresh, it takes another "tastiness" penalty. adding excessive fat and/or salt is an easy hack to make ready made meals a bit more palatable.

I suspect it would be very difficult (ie expensive) to make ready made meals anywhere near as appealing as home cooked without using these tricks.