I do have ADHD and there is so much that I don't think the NTs understand.
Assigning one task isn't assigning one task, it's several tasks in a trench coat. Doing the vacuuming is actually: 1. Getting the vacuum cleaner out. 2. Unravelling the cord and plugging it in. 3. Making sure the attachments are on. 4. Vacuuming. 5. If it's like mine, I have to switch it off, change attachment, change setting, and then vacuum up the small bits around the edges. 6. Unplug, and put away.
Throw in procrastination and executive dysfunction, and it feels like we've been asked to hike to the moon.
So it's good they've actually done their own food, but tidying up afterwards is several more tasks. There are times where I don't bother eating because there's too much involved. Of course they do need to do it, and that needs to be made clear. But I'd consider a compromise of doing by a particular time.
Doing chores etc needs to become a habit, and it's hard to establish, but it can be done. It takes time and consistency.
With regards to executive dysfunction, I even amaze myself at the things I really can't do that other people seem to find a breeze. It's me and my two kids, and I often have to pay someone to do certain things around the house and garden, because they're beyond me. If the girls have never had to lift a finger before, they might not know how to do things. But they do need to be shown, and it might take some time before it sinks in.
As for them not coping uni or living alone, understand that when they HAVE to do it, they will figure it out somehow. At the minute they know their parents will tidy up after them at some point. When there really is nobody else to do it, they will (eventually). Like I really procrastinate with taking the bins out, but nobody else is going to do it, so I have to.
And for her, it's probably easier to let them crack on as they are.