You don't have to be wealthy to have traveled on a cruise ship. The US is also pretty well organized, and generally very transparent about this sort of thing. While China is...not. The US, on a relative basis is also a much cleaner and sanitary country than China.
Replace "wealthy" with "not poor" and the grandparent's point stands.
Or even just interpret "wealthy" in a global context instead of local.
Its also worth noting that Japan's response has been roundly criticized both from within and without. They've kept these citizens in a cruise ship sized pitri dish and the effects are now playing out. On the other hand, they have been more hands off when it comes to monitoring and quarantining people traveling to and from China via air. Most other countries, including the US, seem to be reacting with stronger measures, which may make a big difference.
Logic would dictate that that would continue to be true, since the cost of flying from China is unlikely to get drastically cheaper. So I'm not sure what you're getting at.