exactly, the sign's information is incomplete, so it's likely completely disregarded due to contrary social proof rather than through reasonable assessment.
rip currents apparently kill less than 100 people per year in the US (mostly weaker swimmers who panic).
Best is to turn on your head and understand the rip.
In most cases the rip is very narrow, like 2-5 meters. For an experienced surfer the rip is an extremely good thing, it's a free lift to bring you out to the surf. But inexperienced swimmers panick and try to fight the rip. You cannot fight the elevator, you just have to step out of it. And some rips make turns. You really can predict how the the rip flows by observing the coastline, the wind direction and the waves coming in. When I was surf instructor the most important thing was to explain how this works.
That depends. In some cases it's best to swim parallel to the shore. In other cases it's best to just tread water and let the current circulate you back to the beach.
rip currents apparently kill less than 100 people per year in the US (mostly weaker swimmers who panic).