For 3 people, the federal poverty level is $20,160. $18k is less than that, and in California, you would have been on Medical. Even if you are on Obamacare, not Medical (in California: 138% of fpl and up), under 200% fpl the silver plans are close to free.
I don't really understand your point. I will note that since I could not afford housing for most of the year and struggled to get enough to eat, close to free is not cheap enough.
see eg https://www.healthforcalifornia.com/covered-california/incom...