This is a really important reason why it's not actually obvious that everyone should be getting rooftop solar - not everyone lives in a situation where they can make arbitrary capital improvements to their roof, or even owns their own roof to begin with (I personally live in a rented apartment in a building where the roof space is shared among many tenants). That doesn't mean rooftop solar panels are necessarily a bad idea for people who can do it - it's quite possibly a good idea. But solar panels ultimately require a lot of land area to generate power, and it's often better to use cheap land for this far outside urban areas, than it is to try to put solar panels on the limited sunlight-facing land available in urban areas.

In the US there are certainly cases where the install costs are just too high and the local utility too hostile to solar for the system to make sense.