The RESA for the 05L runway end is within the airport boundary, any aircraft in difficulty has a railway cutting to cross, a row of terrace houses and dozens of landing light supports to get through before it got anywhere near the car park.
Everything an airport does has to be risk assessed so I am pretty sure its been passed as acceptable. Also within 1/2 a mile it becomes a densely populated suburb of Stockport. To my knowledge there has never been any incidents of aircraft or parts ending up in this area (apart from the Viscount which hit the houses on Shadow Moss Road years ago. So how many thousands of movements is that ?
Absolutely minimal risk.