You are correct but many workers in the US (tech and otherwise) are only aware of unions as historical tools of organized crime/corruption, or are libertarian (which gets higher representation in tech circles) and believe the free market will provide for them and/or that unions excessively harm companies. There are likely other reasons but these are reasons I’ve heard from people I know.

These views are reinforced by corporate and libertarian (which is of course funded by corporate) propaganda.