One of my mothers friends, who is now in her 80's, has been retired on a pension for over 40 years. She started working for her municipality right out of high school at 18, and worked 25 years as a clerk to get a full pension. Retired at 43(!) with 75% final pay (annually adjusted) and lifelong medical benefits.
Its totally insane and completely unsustainable. Back in the day people usually keeled over at 65 and the US was viewed as having achieved infinite growth forever, so perhaps back then it was a reasonable but generous offer. Today however it's just straight up corruption and waste to offer benefits like that.
Of course you can. Pensions are a form of debt. If the state is bankrupt, it's reasonable to trim its creditors. Pensioners included. (The politically-savvy way to do this is probably to spin off the pension fund as its own entity and then default on bonds, which the pension fund would hold alongside others. Then leave it to the pensioners to figure out how they haircut themselves.)
The tax base is mobile in a way expenses are not.
I'll speak to this personally. In April 2021 New York City raised its top tax rates. I'm only moderately wealthy, but that prompted my moving out of the state.
Same as universal healthcare, seems like you net benefit by removing these burdens from localities and businesses.
That's one option. Another is better distributing productive capital. Building public housing so its occupants wind up owning it, for instance.
But that's getting into top-down redistribution at the federal level, which isn't in the cards for now. Within the context of cities and states, pensions are no longer a good idea.