In addition to the shorts, when people buy call options - doesn't that mean someone else is on the hook to provide shares at a later date, and they might not hold them at the time of selling the option?
Calls are commonly either covered by shares you own or in a spread where you buy and sell the same ticker at different prices or dates.
I've written cash-secured puts and covered calls a decent amount as an individual investor, the worst thing that happens is you end up buying something for more than it's worth or selling something for less than it's worth. However, it rarely goes wrong the first time and you've made premium from other options many times over on the same security. If you look up the Wheel or Triple Income options strategy that goes into the specifics of it. It works pretty well for high-volume, stable stocks that you want to own anyway.