My package was at the higher end of normal, with $25-27k per year stipend, tuition waiver, and state employees health/dental, but similar arrangements are ubiquitous at good universities.
Sure, lots of students just want to go to work after the BS, and that is completely respectable, but the cost (other than lost wages) is not typically a reason to not pursue a CS Ph.D. in the US.
It's great that it all worked out for you. An advanced degree is impressive. But this issue is all about jobs (and money), and that stipend would be a sacrifice for most people.
A CS student with a BS degree can earn at least twice that amount right out of college. Sacrificing income, for years, in order to earn an advanced degree might not be practical for most people.
Those Americans aren't being lazy, but practical. The experience they gain in the workforce can be valuable. If needed, they could work toward an advanced degree later, especially if their employer covers their tuition.
Most CS jobs don't even require more than a BS degree. And some employers are fine with tech school. I know people without any kind of degree making six figures working in the CS field. They worked their way up, with certifications here and there.
Most H1B IT workers don't have PhDs, or even MS degrees, either, and some have the equivalent of an associate degree.