Lost Baggage
Although many of the cats in this world are domesticated, that doesn't mean that they don't still have their wild instincts. And those wild instincts can make living in a human world very strange and confusing. After all, we have lots of weird stuff that can look utterly ridiculous to those who aren't used to things. Take luggage belts at airports, for example. These cats just didn't know what to make of them.
Of course, we're not sure what these cats were doing in the airport in the first place. But as they can't read, we don't blame them for ignoring the sign telling them not to sit on the belt.