I am pretty sure physics work the same in China as it does everywhere else and that you can find properly built equipment in China, in use, time-tested and proofed. No one likes to live with these dangers.
Btw. Benedict GmbH is located in Austria, the switch from Daves video was made in Austria,
click.
In Dave´s video it was quite obvious that weather and exposure to the elements made the enclosure fail, which then led to a failing electrical contact.
Electricians are usually not mechanical engineers, roofers or plumbers, but you kind of need these skills to get longevity. If you´d told someone 30 years ago to install a switch in an enclosure on top of the roof... it´d better be a good one. Even if it is rated for the UV and IP65 as stated, there are still temperature swings, expansion, humidity changes and vibration from wind that chew on the plastics and create mechanical stresses, depending on how tight the (metal) screws are torqued down.
IMHO the thing either needs a different place or some better mounting, like a piece of sheetmetal above it or be made out of stainless metal in itself with some thought given for the conductors going in and out. But different materials mean different problems.
I´ve seen some articles on fires caused in solar installations over the years, which usually creates the pressure on regulators to raise/set minimum requirements. Maybe the switch is required at that place for firefighters to be able to disconnect it and not get additional dangers due to the energy generated by the panels, it would be bad when the safety device itself turns into the source of the hazard.