You don't have to be a qualified technician to diagnose or work on modern cars. Go out and get a shop manual, a code reader that is setup for your particular OBD vintage, and if the light comes on, plug in the code reader and translate the reading and go from there. Somehow people are making out computers and electronics in cars as being hopelessly complicated - this mysterious thing that nobody can work on. But they're just like anything else. My theory is that if something was made by human hands, then it can be FIXED with human hands just as easily. Sure - there's a learning curve, but that's pretty much with anything... right?
I'm a typical backyard mechanic. We have 3 cars, one that's a pre-smog car that's all-mechanical with no computer management system or whatnot. The other 2 do have these, one from the 90's another from the 2000's. I have only taken these to the shop a total of 2 times. One has 250,000+ miles, the other 150,000+ miles. I do all the work myself, do not have ALL of the special tools a professional mechanic has, and yet somehow working on any of these has never been an issue period.
People that claim that old cars are better because they're easier to work on, I believe are oversimplifying the debate. Simply put, components and parts on older cars tend to wear out quicker in my experience. That and you really need to stay on top of the maintenance - like adjusting points, lubing the chassis, adjusting valves, cleaning and adjusting the carb, and so on and so on. On the other hand, you can usually fix whatever happens to be wrong with older cars faster because there's less "stuff" in the way like wiring looms, emission equipment and so on. So yes - old cars are good in some ways, but bad in others. The problem with most older cars is that the maintenance required to keep them running right is far more frequent and necessary. Perhaps easier to work on? Yes. But considering the necessity to constantly maintain them basically negates that positive.
On our more 'modern' cars components last a LOT longer. The water pump on my '96 Toyota went out at around 200,000 for example. But more importantly, despite having a modern OBDII system with all of the sensors, computers, etc, I have had exactly ONE part of that system go bad - a $40 TPS (throttle position sensor). That's it! I'd say for about 95% of the time I've owned these other 2 cars, the extent of the maintenance for them has mostly been oil, air filter, and spark plug changes. Since so much of these cars use components that are maintenance-free; components that would otherwise require maintenance on an older vehicle, the maintenance requirements for these are significantly less in comparison. Now - are they harder to work on? Yes, sometimes. But working on them isn't out of question for even a backyard mechanic. Many, many people do exactly that, and with even newer cars than mine.
I suspect the people trying to convince us that modern cars are better, are somehow in with the government/corporations trying to tell us what's going on today is alright.
The standard of living in America has fallen so far over the past 30-40 years, it isn't even funny. The cars are getting worse, because most people can't afford to drive anything better anymore. If things continue the way they are in terms of economics and especially politics, we'll be living in a more advanced version of 1984. You can't have democracy with 98% of people getting poorer by the year.