While that stance is about Spain, in Germany only a recent law change brought about by a petition has given balcony solar privileged status, making it harder for landlords to forbid them. Change is possible.
Apartments in Australia work seemingly different to the rest of the world where there is almost never a central landlord that owns the whole building, but every apartment has an individual owner and the rules are voted on by the owners.
Sometimes the state government steps in to make certain rules invalid such as banning pets. But an attempt to let people dry their clothes on the balcony recently failed. And I can see almost zero chance of allowing solar panels since they do have a significant aesthetic impact on the building along with safety concerns around panels getting ripped off in the wind. Most buildings already have solar on the roof but it mostly just powered the lifts and hallway lights.
I spent years renting/owning apartments. Now fortunate to own a mortgage/house.
The amount of freedom open to you is ridiculous. It is like becoming a "first class" citizen - a "homeowner" that the politicians pander to. It is ridiculous.
To deal with apartment living is to deal with bureaucracy/politics/bullshit. And even when the people are lovely - like my last apartment building - the incentives don't align to make for sensible long term decisions for the whole building.
Solar panels with or without battery? Electric car charging? Bike shed? Heatpump-everything? Upgrade building insulation? Arrange the garden to be useful? These are now options available to me on the basis of money alone - no permission from others required.
It is stupid. I know that apartment living can be more efficient per capita in so many ways, better for city planning and public transport etc etc.
But fuck that. A lot has to change until apartments become desirable as anything than a temporary stayover.