Cost. The price increase is 50% to a 100% more then conventional. [0]

Some countries, like France, have passed legislation to make sure large parking lots have at least 50% of their lot covered in solar canopies. [1]

Other studies are trying to convince stores and owners of such places, that the investment is worth it and can possibly even take them of the grid.

[0] https://digitalcommons.mtu.edu/cgi/viewcontent.cgi?article=1...

[1] https://www.forbes.com/sites/carltonreid/2022/11/09/solar-pa...