Client's data is dealt with in strict confidence, sometimes they require a NDA. Some people are under the impression that a recovery company may trawl through client data during the process. This is certainly not the case (speaking for SouthBit) for many reasons.
Client's data is confidential and that fact is respected. Also, think about dealing with terabytes worth of data every week. 'My Documents' is seen merely as another folder that needs to be recovered, more work to get through, more time, more space. Apart from respecting client's privacy, it is actually of no interest. It's work that needs to be done, the goal is to restore the client's data and move onto the next job.
Obviously there are validity and consistency checks in place to verify the recovered data, but this does not require the viewing of any user data. At times the client may request that we verify, by means of opening, certain critical files, but this is as far as it goes.
If something obviously illegal appears in 'plain sight' (child porn for example), then it is obligatory to report it to the SAPS, but this situation has thankfully never arisen.