I used to work somewhere that there was a risk to safety due to lone working with vulnerable people out in the community/ in their homes.
Some of the people I worked with had violent histories or had offended etc.
My employer did care and there were (some) processes in place, but there was still a risk, and tbh the processes weren't really enough, they weren't rigorous or thought through enough to cover all eventualities, we didn't have enough risk assessments or training.
I was in some situations where I did feel threatened/ scared and honestly I don't think the job was well paid enough to justify that.
There was a feeling that my manager cared but didn't really fully understand the risks of what we were doing. Looking back, I wasn't trained properly at all, I was just told the process.
I left the job eventually - but not for this reason. I enjoyed the work despite this but it did take a certain resilience.
What type of job is your friend going for? And what are they worried about specifically?
I think as long as they vet the employer they will be OK, but jobs like this do tend to have an inherent element of risk that can't really be removed, even with good processes and training.