Didn't see the France thing, but did see Gov Cuomo talking about potentially doing that for NY to spread out the taxing of the health care network/hospitals (no word if they will use trains or vehicles). He suggested "downstate" (anything NYC and it's suburbs for those not familiar with New Yawk slang ) people could easily end up being treated at facilities more in the central part of the state that don't have the high concentration of cases that NYC and it's suburbs currently have.
Not 100% sure about the temporary facilities being set up in convention centers, but it was specifically mentioned the Naval Hospital Ship that is NY bound (and it's sibling that is docked in LA, if memory serves) would be used for other patients not suffering from COVID-19, as the ships are not designed for dealing with something like this.
That of course frees up beds in the hospitals themselves though, which are presumably more able to be configured to treat the virus. The point being that "bringing facilities that are capable of dealing with the virus to the people" may not be feasible due to many factors (facility design, personnel availability, etc). If there is a hospital 3 hours away that is all set up and can treat people (well, as best as can be treated right now), and it does not have a n overflow of need for it's own population, that's probably better care than being in a temporary facility that had to be assembled quickly and may not really be appropriate for the tasks at hand.
-Dave