its a big industry lots of money to be made. I work for a company who do loans and our main customer base is the sub-prime market (ie customers who can not obtain finance via the prime lenders.) Its high risk which is reflected in the higher interest rates.
too many people nowadays are taking out loads of credit and bumping companies off or going to debt management companies/insolvency practitioners some for genuine reasons due to change in circumstances and others because they are trying to get one over on the finance companies/the system, therefore high interest charging companies will always be around to try and repair these customers credit ratings, as you say though if you have good credit then dont touch these companies with a barge pole