I agree the the comic is a bit confusing but to be fair it’s in black and white. A red border would mean no entry but a completely blue background would be only bikes allowed.

It makes sense to think that they are car owners that in their regular life wouldn’t tolerate bikes but on holidays find it great.

Checking here https://en.wikipedia.org/wiki/Apparent_magnitude the sun is listed as “about 400,000 times as bright as mean full Moon” so pretty accurate.