What happens to mouldy baked goods (cookies, cakes, etc) if not sold?!

I used to work in a grocery store and the moldy stuff would get thrown out. However, the stuff that was past it's eat by date but still in good shape and not moldy would go to local food banks and churches.

Worked in the bakery section of a grocery store.

I work at the end of the bread game.
I work at an agency where we are given day-old bread by local grocery stores and bakeries to give, free of charge, to people who are collecting groceries at our food pantry.
We rarely (if ever) see moldy bread coming in from the donating stores.
Bread will go stale long before it gets moldy, unless it has virtually no preservatives or stabilizers, and if the pastry or bread contains cheese and if it is exposed to long stretches of summer heat. Other than that, the breads turn rock hard in our establishment and we throw it in dumpsters where it is retrieved by a disposal company, the they treat it like trash and garbage.
Every now and then a woman comes by to pick up a shopping cart of stale bread which she uses to feed animals in the forest near where she lives.

there is no use for moldy food of any kind.
It can be dangerous to animal life just like it is dangerous to humans.
That is why cost control and par levels are important in a business.
Most businesses work very hard to not have anything left at the end of the day. Being able to put out fresh every day is good for business.
I work at a bakery and when a product stops selling really well or business is slow, less is made.
If the downward trend continues, that product is not longer produced; what would be the point.
Thats why there are some items no longer available in stores; the sales numbers just weren't there.

If it has blue mold or for that matter any type of mold, it gets dumped in the garbage. If it is just stale bread, in some cases it will be used to make bread crumbs. At home we do put oldish bread in the food processor and never have had any trouble.

Any items showing actual mold growth would be discarded-things that are just stale are often sold for livestock feed to local farmers.

Depends on where you are. Pigs will eat anything - that's why they are called pigs. I've seen them eat chicken feet that had been buried.

they are disposed of in waste bins and taken to landfills

it gets thrown away