All of the original butcher knives I've ever seen/handled have been thing - and that includes those with Native American provenenace.
That's so they could be sharpened rapidly for the task at hand.
It's also why you see rawhide'wrapped originals that have been sharpened down to 1/4" blades, since they were often sharpened with a rock by their owners.
You'll see good ones - even old ones - at garage sales, estate sales, thrift stores, antique shops and flea markets - so keep your eyes open.
Vaya,
Scouts Out!