Remember that the manufacturers recommendations are designed around keeping the car operational through whatever warranty period they sell the car with. It's not some sort of ideal program and some benefit exists from changing fluids more often than specified.
Specifically, transmission fluid is often considered 'lifetime' fluid that doesn't need to be changed, and, if you follow that advice, you end up replacing the transmission, an expensive endeavor, whereas if you don't, you can typically double its usable lifetime.
You also have to be careful about engine oil, because the margin of error is very small. Most modern cars have an oil minder, and those work well provided the oil itself is in spec.
Specifically, transmission fluid is often considered 'lifetime' fluid that doesn't need to be changed, and, if you follow that advice, you end up replacing the transmission, an expensive endeavor, whereas if you don't, you can typically double its usable lifetime.
You also have to be careful about engine oil, because the margin of error is very small. Most modern cars have an oil minder, and those work well provided the oil itself is in spec.