Modern life means more stress for cats.
On the one hand, cats have very specific needs which must be met for them to feel comfortable. They like privacy and need free access to important resources like food, resting areas, toilets, etc…. Moreover, they must be able to avoid potential stressful situations.
However, modern life means we cannot always provide for these requirements : cats have to live in houses or flats, often without free access to outside. They don’t have a complete control of their resources, and in many cases, are forced to share their living space with other individuals, including us humans, other pets and/or other cats.