That's a fair point... that we live in a world with birth control, and where people are more likely to make a conscious decision to not have kids does change the dynamic.

But I still don't think that any of that would lead one to think that "evolution has stopped". Even if you step back to only focus on what you describe as "the lower educated, lower income" people, there's still competition for reproductive success within that group. If nothing else, sexual selection is still a factor, even if survival selection isn't as much a factor.

Another thing to consider is the "red queen" theory that human evolution and the evolution of pathogens are locked into a (more or less) permanent "arms race". I don't know that anybody knows for sure that that theory is true, but if it has merit, that's another reason to believe that we are still evolving on some level.