It can depend very much on the individual production companies. An HR department isn't actually a legal requirement for a workplace.
Ironically as much as people want to decry them, a big organisation like the BBC probably will have an HR department BUT a lot of production staff won't be necessarily employed by them directly. Instead they'll be likely contracted with a production company (usually for the length of a specific project or a set period) so that's their employer. Just because a show is broadcast on the BBC/ITV/C4 ≠ being a BBC/ITV/C4 produced show either.
And the TV/entertainment industry can have so many moving parts within one production - subcontractors, freelancers, joint productions - that it's really not like any other workplace.
And that's the point. While there's unions like BECTU or Equity, there's no real oversight for the workplace culture. Ofcom regulates what gets broadcast, but not how it was made.
'Management' at the production company I worked for were effectively Project Managers who also handled the employees, with no HR/management training. Hence my issue where you had one boss was really invested in the mentoring and development aspect of being a manager, while the other one was a very hands off, 'learn by doing' person, meaning the exact same job role was totally different based on who you reported to.
