Presumably, the vast majority of the nurses working now have either already contracted and recovered from COVID, and are now likely immune, or gone through months of heavy exposure without consequence. I’m not particularly surprised they aren’t taking it as seriously as we may expect at this point.
I was pretty shocked to start poking around and see that most frontline COVID workers have not contracted the virus yet. I even saw a study that indicated that nurses were more likely to have contracted the virus through social contact outside of work than through contact at work. Apparently PPE is really working well.
It also probably helps that by the time patients are hospitalized they're likely past their most contagious point.