It's because we make life easy and convenient. For stupid people. And we do a good job. And we have more people. So we get better at it.
Imagine a country where you don't get a chance to drive a car until you are 21 years old. And in that country there are no cars with automatic transmissions, air bags, seat belts or safety glass. There is also no collision insurance. So basically there are barriers to entry into the market for driving. Driving is a lot more risky, and failures of drivers are more catastrophic. In such a country of let's say 30 million there are only 5 million drivers. None of them are teenagers, and the fatality rate for drunk drivers is 30%
Now in America we have had automatic transmissions, airbags, seat belts and safety glass for 20 years. We license millions of teenagers. We have comprehensive auto insurance, and we crack down harder on drunk drivers. In other words, we make it easier to be a driver. You need to know less. The costs of failure are not so high. The need for skills are relatively low. It's built into the market and the culture of building cars. And the direction we are going in is to make cars even safer to the point at which they drive themselves. In doing so we drive the intelligence and skill base needed for driving even lower and lower.
In driving, in working, in everything we have improved, we have made it easier for people to be whomever they want to be. Not conforming to high standards of skills, but towards smart consumption. That's why we have more stupid people than anywhere else - because we engineer our society's consumer economy to leverage smarter products, lower barriers to entry, greater amounts of insurance and risk mitigations.
Now you get it.
Do you want America to continue in this direction or not? If you do not, then you are arguing for inequality.