Why have union officials generally not sought elected office in the USA?

[PSOL]

The Democratic party is not a labor party, so they would have no “secure” way of moving up the hierarchy. They also would not get funding, as most business leaders in the United States don’t like union members having a presence period and they would always be overspent in both primaries and in the GE—explicitly and implicitly with tacit support from for-profit businesses who control most of the media.

There are union members who rise to high places at times on the local level sure, but the income differentials between all of Congress and the median voter is more proof of how unique the United States is among anglophone nations in not having a labor party.

[PSOL]

Has there ever been a famous union official in the US who wasn't an obvious crook?  (not that being an obvious crook stops someone from being elected, as proof see nearly every big city mayor in the US or Donald Trump)

This is historically a meme, the notion that union officials were overly corrupt or had extensive mob ties from like 3-4 unions in the 1970s is false, especially so given the corruption swept under the rug by bosses and FBI hyperfocus on union officials on behalf of said bosses.