As a seller without a store, you get 50 "free" listings every month. It is your choice to use the auction format or the fixed price format.
The auction format is limited to 7 days (unless you want to pay a premium for 10 days) while a fixed price listing can have up to 30 day duration.
The choice is yours.
"Ebay would increase it's fees."
You are suggesting buyers would spend more money on eBay because a few sellers would add some "free listings". That is a nice theory but I doubt it has any economical merit. Most listings on eBay (I would guess over 95%) come from sellers with an eBay store where they pay a monthly fee to get a larger number of "free" insertions.
If you feel your listings would be sold and you would "make more money", what is stopping you from listing those items? A few cents per listing?
It was not that long ago that listing fees, including images (called "gallery" then) added up to half the fees paid to eBay. For the last ten years eBay has gradually lowered or eliminated listing fees and increased Final Value fees, resulting in a huge increase in the number of listings available to potential buyers.