In particular: The Tennessee v. Garner ruling in 1985 in which the U.S. Supreme Court [...] abolished the Fleeing felon rule where a fleeing felon who posed no immediate threat to society (e.g., a burglar) could be shot if he/she refused to halt.
Also: In the 1989 Graham v. Connor ruling, the Supreme Court expanded its definition to include "objective reasonableness" standard—not subjective as to what the officer's intent might have been—and it must be judged from the perspective of a reasonable officer at the scene
So it isn't just the subjective sense of fear an officer may feel.
The US is a big place. It's possible to find a few incidents where an officer didn't live up to standards and training and try to make it seem like it's a bigger problem than it is, if that's your agenda. Certainly shooting fleeing people in the back is not "the new normal" in any way that I can see.
Your description of standards doesn't mesh very well with this: https://en.wikipedia.org/wiki/Deadly_force#United_States_law
In particular: The Tennessee v. Garner ruling in 1985 in which the U.S. Supreme Court [...] abolished the Fleeing felon rule where a fleeing felon who posed no immediate threat to society (e.g., a burglar) could be shot if he/she refused to halt.
Also: In the 1989 Graham v. Connor ruling, the Supreme Court expanded its definition to include "objective reasonableness" standard—not subjective as to what the officer's intent might have been—and it must be judged from the perspective of a reasonable officer at the scene
So it isn't just the subjective sense of fear an officer may feel.
The US is a big place. It's possible to find a few incidents where an officer didn't live up to standards and training and try to make it seem like it's a bigger problem than it is, if that's your agenda. Certainly shooting fleeing people in the back is not "the new normal" in any way that I can see.