The "Technology Connections" youtube channel recently discussed awnings too. (And it had more or less the same message as this blog.)
https://www.youtube.com/watch?v=uhbDfi7Ee7k
And that has way more details than this. The only why supplied here is "we forgot" and "AC"
I bet renting has something to do with it too.
I can't just start attaching awnings to the outside of this place I don't own.
The landlord doesn't care if I'm hot in the summer and cold in the winter. He doesn't pay the AC bill.
He might be paying the AC bill. In large buildings the heat and AC is central, and typically is included in the rent. The downside of this is that the decision to run AC or heat is made by the building engineer, and during the change of seasons there might be a warm (or cold) day and the AC (or heat) isn't running.
You can buy portable heaters and air conditioners, plug them in inside your own apartment, and pay the power bill. The AC needs a way to exchange air with the outside but that can be accommodated with a window.
Portable AC units are highly inefficient (also a TC video) because they exhaust the air conditioned air to the outside as part of the exchange.