The problem is that these programs are notoriously underfunded (the financial assistance barely helps. It's like 10k a year if you're very lucky), have their resources misallocated, and do just enough to say that they're doing "something". Their funding is also often lumped in with other welfare "handouts". So when people vote against funding "handouts", they vote against helping people who need it most.
[1] https://en.wikipedia.org/wiki/Trade_Adjustment_Assistance
Where I live, we have Second Career Ontario[1]. When I was in college, several of my classmates were formerly highly paid tradespeople who ended up unemployed and unable to find work after the decline in Ontario's manufacturing sector. The Second Career program funding was enough for them to go back to school for a couple of years. To to best of my knowledge, all of my classmates ended up making the transition to a new career successfully.
I've seen programs in other jurisdicitions that provide some funding for retraining, but not enough funding to teach people enough skills in enough depth for them to realistically be able to move to a new career.