The decline, decay and deaths of Chast's parents had nothing easy about the process. They survived well into their nineties, and never got to a place in which they could have a realistic conversation about their situation. Dementia out ran them. Chast was left to cope as best she could with old age marked by successive emergencies and bumpy declines, none much planned for, nor much cushioned by reliable help from others or institutions.
I could identify with lots of Chast's story. Like Chast, I am an only child; my parents were a decade older than the parents of my age peers; their cultural and social assumptions often seemed to me to come from an alien planet; they lived in the same house for 50 years collecting oddments; and they did not look to medicine to help. However I had a huge advantage over Chast: my parents may have found me an implausible daughter, but they never tore me down. They were good at accepting that what is, is. This is a helpful attitude as we age.
I'm not going to try to summarize anything about Chast's very special cartoon and text creation, though I will say that the book's only character outside the painful parent/child relationship is a professional caregiver of the sort Ai-Jen Poo works with. She breaks through to a dying elder when her daughter can't.
Read it; it is even available for Kindle. (I got it from the library which involved waiting a year till I got to the top of the wait list. This was worth it.)
Here's a teaser -- Chast's pleasant fantasy of what we could wish would be there for elders in hospice when we get close to the end: