Residential rooftops in places like Asian cities are already >50x overcommitted. Land on Earth is a scarce resource. Basically it's only in the US west coast among developed countries has cheap surplus land for some solars.
Go look up US and Norway in the density list[1] before trying to use those countries as the mean average reference standard developed countries. Sort by density and scroll to the top and to bottom. Doing so also explains why EV drivers from basically nowhere else but from those countries appreciate the "full tank every morning" concept.
I picked those two because they happened to come up in news items in the last 48h or so and were in my head.
The UK also has a huge amount of roof-top PV potential, outside the very dense city cores, plus enough golf course space to cover all our PV needs and some I think.
Spain and France and Italy are also doing well with PV and are nowhere near done.
Residential or industrial rooftops are perfect examples. Heck, sound barriers along freeways etc are now even profitable