In all fairness, it's vastly easier to put up a fence over a bridge or regulate firearm purchases than fix systemic social and economic issues wholesale.
I'm not sure it is - we know how to eg address poverty with income transfers and increase availability of free mental health services, and how to raise the temporary revenue for it (temporary because it pays for itself)
You’re 100% correct. These things don’t happen because apparently those who can make it happen don’t actually want that outcome.