You know what .. I'm 30, and I remember being like this myself. I wasn't a bad kid by any means, and they never got an ounce of trouble from me, but when it came to chores I did moan quite a lot.
I think it's hard to go from being a child and being taken care of, to gradually (very gradually!) transitioning into completely looking after yourself.
When I moved in with my DP and his son, after a few months I sent my mum a text saying thank you for everything she ever did for us when we were younger because I didn't realise how hard it was to take care of a home with a child in it - even WITH the help and support of a partner.
It just seems like it never ends, right? But kids are mostly used to doing what they want, when they want, so every little interruption from what they're doing will seem unfair. And maybe it is - but it's the first and vital insight into the fact that life is not, in fact, fair - and that there are lots of things that NEED to be done, that are more important than the things you WANT to do.
You may find it easier to set a rota of chores. That won't help with the odd task here and there like grabbing you some water or your book etc but it will get them into the habit of being more helpful - and if the chores aren't done they don't get to do x, y or z - whatever you think will work for them!
My DSS ONLY has to do the dishes, and not even dry them, and even that's like world war three.