I've had dozens of 210's arrive at my shop on flat-beds, due to rusted spring perches. Not one was involved in an accident. Like nhdoc says, they usually fail at very low speeds, minimizing the potential for serious damage. Also, many more are discovered during routine inspection, long before they fail, thus preventing the ride on the flat-bed.

I think MB should be taking better care of 210 owners with respect to the spring perch issue, but it's not like they ignore them either. MB routinely pays a portion of the repair bill, usually half. If you're the original owner, and you've serviced the car at the dealer you bought it from, there's a good chance your dealer will pick up some, if not all of the remaining amount. On the other hand, if you're the third owner, and you've never serviced the car at a dealer, be happy if you get any help at all. That's just the way it works.