This is broadly true of cheap thumb drives, but not true of all USB flash drives. The larger ones generally do support secure erase. E.g. the Crucial X6. I don'

This is broadly true of cheap thumb drives, but not true of all USB flash drives. The larger ones generally do support secure erase. E.g. the Crucial X6. I don't know if these use secret vendor commands, or if they use the standard SCSI "sanitize" command.