Why folks in developed (and come developing) countries becoming impatient and intolerant today ?
Folks are not intolerant because of Politics or Religion, instead folks are intolerant because the eco-system does not require them to be patient anymore.
Lets go back a century when resources were not easily available. At that time for example since there was no cold storage and no high speed transportation system, people had to eat what was locally grown in their area. Farmers too were totally dependent on nature for growing crops as there was no irrigation system, fertilizers, etc. So in case there was a bad monsoon season, the growth of crops was not adequate. In that case people had to suffice as to what was available even if it meant to skip a meal since there was no other way to fill in for the shortage. This build resilience and Patience in people.
But now a days every kind of food is available all round the year 24×7 and we can get anything we want at anytime. Thus if something is unavailable we get impatient because we never learnt how to wait patiently for a meal or food. Also if we see from health perspective, eating locally grown crops and vegetables are suppose to be healthier rather than consuming stuff grown from other regions.
Since now a days we have plenty of resources at our disposal, we want things to happen when we want them to happen. We dont have the habit of waiting for it. But in earlier times when resources were rare, people were dependent on nature and had to wait patently for things to fall in place (such as next growing season of the crop for ample food supply in above example) since there was no other option.
In my opinion this is the reason we as humans are becoming impatient and intolerant today. And this affects our mental health as well.