The one time I tried to negotiate for a director position they responded along the lines of "Oh we're sorry if we implied that this was a negotiation. You can accept or decline the offer by the end of the week."

LOL we might have applied at the same company. That's almost word for word what I've heard in the past: "Oh, sorry, we must have been unclear: the offer is not negotiable." I said NO and they said "OK, thanks for applying."

I’m an average software engineer and I can’t remember a time where I took a job I didn’t negotiate the salary on. Companies that refused to negotiate were the last offers I’d consider and I end up not taking their offers. I was often better paid than my peers. And my professional accomplishments are far from exceptional, I’ve never worked for any companies you’d know, I have gaps in my CV.