The trunk lights I've seen on Chrysler products were usually operated by a plunger-style switch (like the side door courtesy light switches) rather than a mercury switch. The light was attached to the sheet metal under the rear window area so it illuminated the spare tire area and the trunk floor area. A malfunctioning mercury switch here could go undetected, but the wiring could be unplugged from the plunger switch easily, if needed.
Underhood lights, if malfunctioning, would be more visible at night, should anybody desire to look for an unusual light from under the hood, I suspect. They seemed, to me, to be more prevalent on higher-line GM cars, though. Might there be a message there?
Underhood lights could also be a nuisance should the hood be up for an extended period of time. Many times, the mechanic would physically bend the bracket (on the GM lights) to turn them off so it would be unnecessary to unhook the battery.
Just some thoughts and observations,
CBODY67