>Why these people aren't paid wages where they can afford to exist is a whole rats nest of economic theory that we don't really need to get into.
It's not a rat's nest of economic theory. People are paid what it costs to replace them, aka opportunity cost. Obviously the very existence of businesses and workers means someone is willing to work for those wages, which means they can afford to exist...since they exist. Whether or not it's a quality of life worth having is a political problem that needs political solution (i.e. basic income).
Based on the experiences of my businesses and people I know who have businesses in cities experiencing rising rent, wages are going up significantly for blue collar work, but at the end of the day, there will always be someone at the lowest end of the pay scale, and that will be the person who is doing work that many others are willing and able to do, which is usually food service/janitorial/security/etc.