Near me is an area that was listed by Guiness as the "worlds' largest trailer park."
Most trailer fires seem to either be somehow associated with either the waster heater, or back rent.
We also have major areas of "manufacturered housing." Ultimately, if you break the house into small enough components, we all live in a house that was "brought in on a trailer." The major difference between a 'trailer' and a 'manufacturered home' is that a trailer can be moved; the other, once assembled, is there to stay. Would you call those high-rise buildings made of pre-fab parts "trailers?"
Another issue is whether or not a "mobile home" is "real estate." Unless certain steps are taken (setting it on a footing, etc.), the trailer is not subject to permits, inspections, etc., as is a "normal" home.
Whatever the faults are in the installation of 'trailers,' let's not forget the barely adequate practices often found in today's stick-built 'McMansions." Add to that the presence of box stores, and the willingness of the homeowner to attempt anything, and we have a lot of people setting themselves up for a fall. At least the pictured installation appeared to have been left alone since the dat it was installed.
