Window units don't work in most of Europe because our windows aren't compatible with them. If they were, I would have one.
And again, it doesn't solve the core cause. If you want to cool down your home, your first step should be to stop heat from entering. If you can get the same result from €900 of shades and €100 of AC as from €1000 of AC, you'd have to be stupid to go for an energy-guzzling AC-only approach.