I can agree that it involves work. And I recognise that, for many people, it will be incredibly "hard" work. But speaking from my own subjective experience, I can't say that I ever really found it to be "hard work". Except, perhaps, the sleepless nights in the very early days.
Of course, I did all the ferrying around to clubs, helping with homework, hosting friends and making packed lunches etc. I guess they all involved work of a sort, but it certainly wasn't what I would describe as "hard" work in the same way as, say, my job, is hard work, or even stuff like cleaning the house! None of that stuff was mentally taxing, emotionally draining or physically exhausting in any way. I didn't have to psyche myself up to do it. It wasn't ever an effort.
And yes, I suppose there was a lot of what I guess some people might describe as "emotional labour" involved in listening, supporting etc. But as I said earlier, that stuff usually felt pretty effortless to me, and we were fortunate in that dd didn't really experience any major struggles. I get that it must be incredibly difficult for parents having to support children who are unhappy or unwell etc. And refereeing between children's squabbles etc.
I do understand what you mean about enjoying your job while simultaneously finding it hard work. For me, that sums up my paid work very well...I love what I do, but it also requires a lot of effort and endurance. I never personally experienced parenting in that way. I don't think that's because I'm a better parent than anyone else, I just think we were lucky to have been given a very easy ride.