That’s just the thing - there’s not a pathway to citizenship for everyone. Most of the time (not all), you need an employer or family connection in order to get permanent residency, which is needed before citizenship. Usually, you get a green card because someone else submitted a petition on your behalf.
For people who cross the border illegally, or overstay their visas, normally in order to adjust status, they need to have an immediate relative (spouse/parent/child) who is a US citizen sponsor them. Jorge and his family, when they came over, most likely didn’t have any immediate US citizen family members who could sponsor them, basically leaving them in limbo. Now, undocumented immigrants often have US citizen children, but they have to wait until they’re 21 to sponsor their parents. If they have a US citizen spouse, the spouse could sponsor them, and it seems that Jorge and his wife tried, but somehow (and I don’t have details on why that was), it didn’t work and he ended up in deportation proceedings. Jorge’s parents would have had no way to become citizens, unless Jorge himself (or a sibling) was over the age of 21 and became a citizen and sponsored them. It’s complicated. In comparison, citizenship is easy in my opinion, but you have to be a permanent resident first (have a green card), and getting that is the hard part and why so many don’t do it.
It’s not as simple as saying, “well, why didn’t they apply?” They didn’t apply because most likely they didn’t qualify, and it’s not as simply as merely registering your interest and intent.
When I worked in immigration for a non-profit, it was a lot of things to keep straight, and every single case had to be analyzed thoroughly. I liked it a lot and continue to try staying up to date on the shifting regulations, but it was sometimes a headache.