Somehow, the guys who do this stuff always have parents who claim they're not boy racers, merely "car enthusiasts."
Various of us at No Minister have plenty of experience driving reasonably powerful rear-wheel-drive cars. In my experience it definitely is quite easy for them to lose traction while cornering in the wet - it's happened to me plenty of times with wet asphalt on roundabouts and suchlike. At the kind of speeds you normally do in a built-up area, this isn't a big deal - you feel the tail start to go, you correct it and take it as a reminder that wet roads mean you should take corners more slowly than usual. What doesn't happen is that you fishtail all over the road and sweep across the footpath fast enough to kill pedestrians and severely damage your car - unless, that is, you're flooring it.