It's not just the pizza delivery story lines. Almost everything about porn is fake.
The settings are fake, the lighting is fake, the actors' physical appearance is fake (make-up, post-processing, etc.), the emotions are fake. Often the actors lie about their age, their sexual experience, etc.
Someone on 4chan, a forum with many devoted experts on porn, said that most of the big penises are fake (i.e., prosthetics), too. (No one further down the thread contested the assertion).
I've seen prosthetic pussies in porn too (most notably in a movie where a man purportedly inserts nearly his entire head in a woman; the plastic prosthetic female sex bits were glaringly obvious).
The settings are fake, the lighting is fake, the actors' physical appearance is fake (make-up, post-processing, etc.), the emotions are fake. Often the actors lie about their age, their sexual experience, etc.