A nonstick coating is built specifically to keep food from forming the bond that makes fond in the first place. Browned protein fuses directly to bare metal at a molecular level, and a coated pan has no exposed metal for that fusion to happen against. Whatever residue does turn up in a nonstick pan is thin, patchy, and barely worth deglazing.
Why protein bonds straight to the pan
Searing does something more direct than "browning" suggests. When raw protein hits a screaming-hot pan, it denatures fast, and the fragments left exposed on the surface — the sulfur- and nitrogen-bearing pieces of the protein chain — form weak, temporary bonds directly with metal atoms exposed on the pan itself. That's the real reason a steak resists being moved for the first minute or two: a thin layer of it is, in a literal sense, bonded to the pan. As the moisture underneath finishes cooking off and the crust firms up, the contact area shrinks and the food lets go on its own. What stays behind on the metal afterward is the fond — fragments of that same crust, now bonded to the pan instead of to the meat.
Why liquid lifts what a dry spoon can't
Scraping a dry pan with a wooden spoon mostly just polishes the crust. You're trying to break a chemical bond with brute force, and it doesn't work well. Liquid does something different. Water, wine, and stock are all polar, and so are the browned compounds that make up fond, since they carry many of the same nitrogen and oxygen groups that let them bond to the metal in the first place. Once liquid covers the pan, it starts pulling on those bonds chemically instead of mechanically, and the heat and steam finish the job, lifting fond off the metal and into the liquid as flavor rather than crumbling it into dust that just washes down the drain.
Why the same residue is fond in one pan and scorched junk in another
A nonstick coating is built to have almost no surface energy, which is the property that lets molecules stick to something in the first place. There's no exposed metal for protein to bond against, so instead of building a layer the way stainless steel or bare carbon steel does, food in a nonstick pan mostly just slides.
Any dark residue that does show up usually isn't fond in the useful sense. It's a spot where a hot burner ran past what the coating can handle, and food scorched onto the surface the ordinary way fire scorches anything, not through the bonding process that builds usable fond. That residue won't dissolve cleanly into a deglazing liquid, because it was never chemically attached to the pan the way real fond is. Bare metal is what turns browned residue into something you can pour a cup of stock over and call dinner. A coating just turns it into a cleanup problem.