Because the people profitting from the direct causes of many of these issues, fossil fuels and industrial meat, started a culture war with the people who were concerned about them.

Anyone who popped their head up to address any of these problems was attacked and undermined by very well funded adversaries.

Any crank that argued against them even being a problem got promoted.

We struggled to get them to stop poisoning humans with lead and cigarettes and poverty for the same reasons.