Poultry are handled differently by the USDA than
other animals. They are not covered by the
Humane Methods of Slaughter Act which 
was specifically intended to reduce extreme cruelty to 
animals in the food system (of course, it doesn't 
really work but that was the intent.)

Poultry are instead covered by the Poultry Products
Inspection Act which was designed to keep
poultry products "which are unwholesome, adulterated, or otherwise unfit for human food." out of the
food system. The USDA considers humane treatment
of the birds to be a side effect of the 
inspection process. As in - if a bird is scalded to
death instead of being dead before it gets to the
scalding tank, then the carcass will be red and will
fail inspection causing the company to lose
money.  There are no real consequences for 
mistreating birds as a quick read through the 
spreadsheet below will show. 

The inspectors in poultry plants try to enforce
Good Commercial Practices (GCP).
When they find violations of GCP, they can write a 
Memorandum of Interview (MOI)
which means that they have talked to the plant
about the problem or, they can write a
Noncompliance Record (NR) which is a little
more serious but still only a problem 
for the plant in as much as it is possible for
the general public to find out about them and
many times it takes a FOIA request to find those.

In the file below, are NRs (column P) and
MOIs (column S) from the most recent GCP
reports. The original reports are here.