Unions both necessitate and foster increased class consciousness—the recognition that workers and management have fundamentally different interests. This awareness highlights that all parties primarily seek to extract money from the organization, transforming distributional conflicts into explicit confrontations.
From what I can see on this thread, academics struggle with this framing. They view their profession as intrinsically valuable, motivated by education and research rather than primarily by income. This perspective also involves elements of vocational reverence and self-sacrifice (and can of course lead to exploitation). Unionization effectively transforms the institution from being the central identity and purpose for staff into a contested economic marketplace.
And, as academics seem to only be vaguely aware of themselves as "workers," the idea that the PhD students saw themselves as workers and wanted to join UCU came as a bit of a shock. So, the way to deal with the discomfort of seeing their job as economic is to say that PhD students in the UCU are only capable of student politics. Seeing your doctoral student in your union also messes with the very hierarchical nature of academic life and the idea of "paying your dues." It may also be discomfort with the reality that young people have been given a pretty raw deal economically comparied to their older counterparts.
In the UK, this academic mission that academics believe in has already been abandoned. University Vice Chancellors have evolved from senior academics into businesspeople with academic backgrounds (or sometimes not even that). They openly treat universities as profit-seeking enterprises targeting student fees, grants, and commercial ventures. While paying themselves substantial salaries and benefits, they actively suppress non-management compensation, unlike the previously modest salary differences. Some have called this the enshittification of the sector.
The concept of UK universities as mission-driven centers of learning effectively ended approximately 15 years ago, following a gradual decline over the preceding 30+ years. I don't think the larger public sees academe as intrinsically valuable anymore--education is now only seen as relevant when vocational. Education is not important, just the diploma and wage it will provide.
Academics seem to resist acknowledging this reality, finding it easier to criticize unions like UCU than participate meaningfully. Despite imperfections in UCU which I will absolutely acknowledge, unions provide leverage, but only if people participate.
But, well, union participation is often tedious, thankless, and consumes personal time—similar to why even those concerned about political issues rarely take concrete action through campaigning or petitions.
I'll also acknowledge that beyond common concerns about retaliation and membership dues, academic unions face unique challenges. The widely varying workloads and responsibilities across academic positions make standardized representation difficult. Additionally, since unionization benefits some more than others, those who might gain less have little personal incentive to participate.
This ultimately reflects individualism at work in academic settings which I discussed upthread.
I thus think HE in the UK is pretty doomed and will probably implode. Unless there is market demand for a specialism that is industry related, the permanent academic post will go the way of the dodo. Heck, a lot of academics don't even have the job security of primary or secondary school teachers, who last I saw, did get a 5.5% pay rise in September. Junior doctors did, rail company workers did, but not the academics. And that is not just down to UCU (see above). It is an easy cat to kick...