I’ll be honest, I don’t understand why the hell we’re not already doing exactly this.

I think I was maybe three or four years old when it finally clicked that you always ask for more than you want / expect. Couldn’t elucidate it as such, at the time, but I certainly can now. Corollary is that if you make reasonable demands, expecting good faith, you will get bartered down to zero. Generations of market stall sellers can attest to that one the world over.