According to a friend who's been a sorter (among other roles) at UPS for like 25 years, this is correct. However, at least where he works, they've reduced the staffing number requirements, and are offering to send people home if they're "over staffed" (they aren't, they never are), and are softly suggesting/requiring that those who stay work OT. So my friend, who needs to pay his bills, stays and ends up working 2-4 hours OT every night. He's cleaning up, but management has made it abundantly clear that the OT - while not "required", is absolutely required.
So they reduce headcount and punish staff for their new raises. Payroll costs stay about the same (subtract those that went home, add the OT), and remind the employees who their masters truly are.
In my friend's case, he's been there so long he would take an enormous pay cut trying to leave.