Good point. You are absolutely right that used car chemicals are a problem; they have to recycled or disposed safely. That certainly is a drawback. I think the long-term issue comes down to whether the regular change of fluids will let you keep the car longer. Then you are balancing the waste generated by the used chemicals versus the waste of an entire car whose useful life is over. Could the car's functional life been prolonged for several more years with meticulous maintenance? Typically, I think the answer is yes. Then, you not only save on disposing of the plastic and steel in the old car, but also save on the mining of new raw materials, fumes from the paint, and the energy used to make the new vehicle. Another benefit to meticulous maintenance is that you reduce the probability of component failure at some inconvenient or dangerous time.

Your point of the prescbibed lifetime is an interesting one. But what is "lifetime?" If it is 10 years, then the factory-fill transmission fluid might be all right (sometimes). But new cars are so well machined and protected from corrosion, I think they should last much longer than that. So, by neglecting to do maintenance, what you are really doing is inflicting the next owner with the burden of having to catch up with undone care. Often the secondary owner is not that well off, so another burden on his life....