I am going to take a different perspective on this topic.
Philadelphia is general is a blue collar city, is it good, is it bad, is it neither. Why???
If you look at the corporate tax structure, it is very unfavorable for businesses to be located in the city of Philadelphia. It is better for them to be located in Delaware or Montgomery county. Currently Philadelphia is the poorest major city in the country. If the working class goes from blue collar to white collar than this will shift the balance and the entire market goes up.
On the other hand let's assess the geographic placement of Philadelphia. It is located 1.5 hours from NYC by car, 1.5 hours to Baltimore by car, and 5 hours to DC. It is a gateway city that must be passed for trade purposes but can be missed for passenger purposes.
So to sum it up...
Philly is a poor blue collar city that is located in between other major east coast cities. Politicians don't necessarily want more business in the city, and the local people don't want more money. If more business or better jobs where in the city it could easily get price inflated and gentrify locals, as scene in some neighborhoods.
If you don't believe me look into government subsidizes rates.