With respect I think it's a bit excessive to start questioning and comparing job roles. Every company is different - massively so. And roles can even adapt and change. Case in point; I started in another role before becoming an Estate Manager with my employer. I undertake my role differently to my predecessor and my successor will likely make it a different role too. My predecessor was much more office/paperwork based. I prefer to be on the tools more than half the time. With an electrical background, it was obviously noted I had a bias this way - I undertake work to this effect and it's now reflected in my terms of empoyment following an annual review.
Obviously I'm in a funny position, because being the Manager, it's ultimately my job to also decide on the competencies required to undertake electrical, and other work at our site (and to this effect I have relevant qualifications, partly supported by my employer) - but my point is, Maintenance in one Employer may be very different to somewhere else.