Arranging PET bottles of water will scare cats away from a building.

WRONG

I wonder if they are other countries where people are believing this BS… to think that cats even notice this?

Even Wikipedia Japan warns about Cat-PET-Bottles in this article about PET-Bottles:

PET bottle incident –
There has been false information circulating that filling PET bottles with water and leaving them around building entrances will discourage alley cats. This resulted in an odd kind of “water-filled bottles being placed everywhere” spectacle. However, some cases have reported that these bottles have caused incidents when the water in a PET bottle focused sunlight enough to start a fire.