I have american colleagues who are undergoing various treatments and they know they can't lose their job because their health insurance would end and they cannot afford to pay for it without a job. Yes some kind of medicaid or other would eventually kick in, but it would still mean potentially months of going without cancer treatment because you lost your job.

In (most) European states it's just not a concern that anyone ever has - if you are getting treatment under national health service then it has nothing to do with your employment status and any treatment would just continue. If you need time off due to ilness it has to be paid for as well(employer only pays for a while, then the state takes over).