They won't. They issue claims well into six figures every year. Believe it or not, well over 90% of those end up being CCJs in default because the low-hanging fruit on the gullible tree who receive them, have no idea how to respond, ignore them or don't even know about them because they never updated their address on the V5C the last time they changed address.
The few that are defended, are discontinued because there is much more profit for them in the vast majority that are not.