Why is the situation you've described fundamentally different than the situation I've described? Individual on a fixed income that is too low to pay the cost o

Why is the situation you've described fundamentally different than the situation I've described? Individual on a fixed income that is too low to pay the cost of living in their home and must therefore move, because the fact that the local economy has improved (making things more expensive) doesn't imply their income improves to match it.