Most are terrified of their constituents. If there are mass protests and people pressuring constantly they will listen even if this vote was unconditional.
But this is why they work so hard to keep us just poor enough we can't afford to revolt but not so poor that we have nothing left to lose.
I feel like the systemic response to BLM completely negates your assertion. If mass riots don't get even token police reform as a result, then it's pretty clear that our leaders don't give a shit about anything short of someone putting a gun to their head.
Hey the NYPD created that discipline matrix in response to it to hold cops accountable. Why yes it is in the news recently because that corrupt police chief just weakened it, why yes he has already weakened it before and yes Garcetti had whined about how unfair it was and weakened it already before that, and yes both of them are alleged to have ignored it and let cops get away with things on the matrix.
They're terrified of their electorate not voting for them. If everyone has already committed to voting for them regardless there's no leverage to exert pressure