It is only the trolley jack that's in that set, and may have a safe working load lower than specified. (According to the Recalls website)

Given the fact that there's pretty big safety margins built into these standards, and the fact that you shouldn't work under the car when it's on a trolley jack, it's hardly a big issue.

Much less safe is using bricks or breeze blocks / concrete blocks to support the car while you work on it, as these have very low thresholds for shattering. Perhaps not such a big problem with light cars such as Minis, but lcertainly less safe than using Super Cheap brand jack stands.