A patient zero on a new york subway could infect a few people and they would be hard to trace.
Although it's not probible it is scarier than "can't happen"
I'm sure it's not the case for everyone, but when most people develop flu-like symptoms, they usually end up quarantining themselves for a few days while it resolves. If they can't do that, social etiquette dictates that they avoid physical contact and close proximity, wash their hands regularly, not share food, etc.
I couldnt see any studies for this. The best data I found was a per capita doctor rate where countries with universal health tend (but not absolutly) to have more doctors per capita which 'may' indicate more visits assuming doctors are created by demand (loose I know): http://gamapserver.who.int/gho/interactive_charts/health_wor...
In the US I've had colleagues that were told to go home. Even with overwhelming evidence that they should not be at work they came anyway. Unfortunately, some could not afford to be sick. Rather than take the personal financial hit they caused the entire operation to slow/stop as other workers called in sick.
Unfortunately social etiquette in the US means to show you are productive even with sickness. "See how productive I am, I've got the flu and I'm still doing this presentation!"
Insurance company execs are not likely to be treating Ebola :-)
It's unlikely that either system is particularly set up for Ebola style infectious illness.