America is full of long, straight highways on flat, featureless countryside. It's absurdly easy to get caught in a pileup when fog rolls in. Just watch this video where a profane old lady crashes in low visibility.
This video was reportedly recorded on June 19th and came with the following caption.
an old lady has difficulty driving through fog and becomes part of the problem ahead of her
she's the one driving the F-150
Drivers are rarely sufficiently cautious when heavy fog rolls in on monotonous highways. It's not just Americans being poorly trained drivers, either. Absolutely massive accidents happen with some regularity on the German Autobahn.
If you're not comfortable to drive in heavy fog (we hear this driver say she can't even find the headlight switch, either from unfamiliarity or fear), slow down.