This is a picture was reminds us that cats like to rest in high vantage points. By “vantage point” I mean a position from which a stray or domestic cat can view the terrain around him or her. It creates a sense of security. It reassures a cat and allows her to be in a stronger position which protects her. Most of the time domestic cats sleep off the ground.
These are obviously street cats who have found the nearest available high vantage point. As the motorbike seats are black they may also be warm because black absorbs heat from sunlight. It is common knowledge that cats love warmth. In addition, these cats may have jumped onto the motorbikes after they were parked at which point the engine would been hot providing further rising heat.
We see this a lot with the wild cat species. We see leopards rest in trees. Some African lions rest in trees. Some wild cat species take it a step further and actually live in trees most of the time such as margays and clouded leopards. These are arboreal animals.
It is mandatory to provide a nice high vantage point for a domestic cat to rest in at your home. Nowadays 90% cat owners realise this and buy a cat condo of some sort which does the job. There are thousands of varieties of cat climbers and cat condos allowing a cat to move vertically. Domestic cats think vertically and it’s in their DNA to travel vertically. This aspect of the domestic cat can’t be overemphasized. Nowadays 90% of cat owners realize this thanks to the Internet, primarily.