To answer your question, Yes, with no food or water, I'd say thats pretty bad.
The pen is bad too, but not bad enough for the authorities to do anything.
I totally understand what you are saying, you are a volunteer, you are doing what you are told, and your hands are "tied" to do anything else.
I have been in the same position.
I am sure the resuce is working with the authorities. They are probably documenting every time they feed the horses or help out, and turning it in.
In the meantime, they are just tryign to keep the horses alive and ok. While the ower is trying to make a "buck" from the rescue.
And you are right, the main rescue I support, buys most of its horses for under $100 each