Actually some places are already working in those solutions as well, like basically painting roads white, and it has been proved that in those areas it's not as hot in the summer so there is less power consumption for AC. (see https://www.cbsnews.com/news/los-angeles-is-painting-some-of...)

However, that is still very expansive, and you need to paint a lot of surface areas (counting those that you can even paint) for it to make a significant difference (in world-wide terms).