Wiping disks has not been possible and has not been trusted since embedded controllers on the disk-drives took over bad-block remapping in the late 1980-ies. I

Wiping disks has not been possible and has not been trusted since embedded controllers on the disk-drives took over bad-block remapping in the late 1980-ies. It's even worse with SSD drives, where the "hidden reserve" many times larger. Wiping is of course better than doing nothing, but neither lives up to the requirements of GDPR. Where wiping disks is sufficient, for instance "internal reuse", it is always some number of specified writes, followed by writing all zeros, so both the donor and receiver can verify the disk as empty. Note that wiping a SSD with all-zeros is likely to be optimized out by its embedded controller.