In the US most decent employers offer health insurance(where they pay a part and part comes out of your paycheck every month), and that covers any kind of medical care including a trip to the ER. Worker’s compensation is a whole different thing though. That only covers an accident on the job and typically they’ll pay the majority of whatever medical costs the insurance doesn’t end up covering(deductibles or whatever) and the employer will also be on the hook to help with the fact that you can no longer work for possibly several months while you heal. I’m not totally versed in the specifics but essentially you’ll get some paid time off.
Lack of worker’s comp is really what made me stop doing bike messenger work for the different App-based companies. If the money was really good maybe it’s worth living on the edge. But most days after taxes you’re not making minimum wage for a job where if you get in an accident you’ll be trying to survive on welfare/disability and possibly laid off from your second job depending on the job and how long you can’t work.