My recent experiences with some cheaper consumer grade lawn equipment has fully convinced me that the manufacturers intended on it being fully disposable no matter how well you care for it. I had a nice 7HP Briggs engine that always had torque like mad. Then it began to really lose power and bog easily. I checked the valve lash and adjusted. This improved things but not by enough to matter. The real problem was that the camshaft is made of PLASTIC and that the cam lobes had basically worn down to nothing. It was hard to start and wheezy and would only stay running at a high RPM. It barely had enough power to sustain itself at low RPM and finally got to the point where it would overheat after a few minutes and shut off. I always liked this engine and thought about replacing the camshaft but it had gotten to burning quite a bit of oil so junked and and replaced it with a Honda GCV160 series on the same deck. That engine was pulled in perfect shape from a deck that had rusted through.
I got to looking at a parts diagram for the Honda and it also uses a PLASTIC camshaft as well as a timing belt which "will last the life of the engine." Apparently these have broken or popped off the sprockets on many people and there are DIY Youtube videos on how to replace them. My gut tells me the average person is going to roll an otherwise perfectly good mower out to the curb when this happens. For now, the donor Honda is working great on the old deck I had been using but I wonder how long that will last.
Then there is the Briggs and Stratton engine that came out over the past few years where they claim it never needs an oil change for the life of the engine. They probably also have a plastic camshaft riding against steel flat tappet lifters to limit the life of the engine.
I am curious how many cars/car parts have gone this direction. I know many parts are now plastic but this isn't really a bad thing for many applications and may actually be better. For example, some valve covers and intakes are now plastic. Body panels are plastic. These resist minor denting and rusting much better than steel. Overall it seems that most modern cars will go farther and farther between maintenance and will last longer than ever before because of improvements in machining, materials engineering, lubrication, and such.
In my line of work (computers/electronics) I seem to be dealing with products, especially the consumer grade, being made to a lower and lower standard with each new model. They are also being made harder to service to the cost to service meets or exceeds the cost of a new unit. I had a laptop in from Wal-Mart with a failed component. The problem was that everything was integrated onto the motherboard so the entire motherboard required replacement instead of just the failed component. Business grade models are not made this way.
Any cars going this way as of yet? I know many would consider the Chrysler 2.7 to be a disposable engine but how about something current that really limits the life of a car?