There is a quantifiable difference between shipping a horse 100 miles to slaughter, and 1000 miles.
Again... Before the ban there were precisely two horse slaughter plants still operating in the US. I think one was in Illinois, one in Texas.
To horses in Washington, I don’t think they see much difference in which highway they shipped over, they traveled a long ways.
The days of old there were more plants... back when pet food companies were still buying it. They haven’t been for years... because it’s not safe, people didn’t want to buy it, and there is plenty of other, better meat available. But it’s been decades since they went out of business.
There are still rendering plants, that will cook remains down for fertilizers and whatever else... there is one of those in this state. And they will (the one here will) euthanize the horse for you... but that is a very different process than what we’re talking about.