This issue was first posted a while back, but not resolved for the user reports. (
The SCORM report uses the scorm_get_sco_runtime function from mod/scorm/locallib.php to get the "Started on" date. It actually queries this value from the database (scorm_scoes_track WHERE element='x.start.time').
The user report, however, gets it's "First access" value from the scorm_user_complete function in mod/scorm/lib.php. Oddly, this value is first set to the current time and then reset to the timemodified if the current time is greater than the timemodified (which it always would be).