It is different in each state. The feds get blamed for a lot that the states do. Anyway, that is another rant.
Before they started the NPIP program, pullorum was a lot more common. Now it is pretty rare. How common would pullorum become if the NPIP program disappeared? Well, it was a lot more common before the NPIP program started.
I agree with SpeckledHen. NPIP gives a false sense of security. It was designed for a specific purpose, not a cure-all. A skin cancer screening does not protect you against typhoid, pneumonia, or the common cold. It doesn't even protect you against other kinds of cancer. NPIP was designed for a specific purpose.
Editted to actually answer the OP's question. I don't participate but I don't sell hatching eggs, chicks, or chickens. I do not always get NPIP certified hatching eggs, but if I got hatching eggs from out of state, I'd probably want NPIP eggs. I don't knowingly violate the law just because I think I can get away with it. That's my personal ethics.