The average rent is per household as each household needs one place to rent, whereas the average salary is from each working person. A lot of households have 2 working people resulting in more income than 1 working person households. If everyone made the average salary, 2 working people would bring $102k while 1 person makes $51k. 2 people would be able to afford the $2000+ rent but 1 person would rent a $1000 unit for example. So those averages can’t be compared the way you are doing.