Application fee (USA)

Application fee (USA)

I'm in the middle of looking for an apartment around Philadelphia and I've never under stood how each place can charge a different fee they call application fee?? Like starting from 25.00 to 65.00 dollars non refundable let me ask if the price is lower does that mean the worse your credit is, and the higher you pay means the better your credit is. LOl, most places pay one fee to check your credit and this is how they rip off the lower class of people trying to find a place to live.