Or they report it to their managers, and those managers are too afraid to report it up the chain to contradict an ambitious timeline.

Or marketing. I've heard innuendo that at Apple, marketing has vetoes

oof i can’t imagine using it in my country where it’s 30 degrees celcius and above on average everyday.

I haven’t noticed a heating issue and I live in a very hot climate. So, it’s not universal.

People have used it in very hot areas and it has been fine, with no overheating issues.

People have used it in very temperate areas and it has turned into a small furnace.

The controlling variable is almost certainly not ambient temperature.

When developing a product you order "process corner" chips that are primarily used for testing the memory timings (through a process called Shmoo) to make sure it is stable. The "FF" class of these chips are also useful for testing thermals as they draw the maximum power you will see with the silicon lottery. So assuming Apple did this properly they should have had a good idea of what the product temperature is at the operating temperature extremes.