No, they were often NOT allowed to flee. Sometimes they fired on the humanitarian corridors travelling back to Ukraine, sometimes they forced people in occupied territory into "filtration camps" and took their passports to give them new Russian passports. People with Ukrainian passports weren't allowed through border checkpoints.

https://www.hrw.org/news/2022/03/08/ukraine-russian-assault-...

https://www.theguardian.com/world/2022/apr/26/russia-accused...

https://www.amnesty.org/en/latest/news/2022/03/ukraine-human...

https://www.npr.org/2022/03/08/1085097957/what-the-war-in-sy...

https://www.reuters.com/world/europe/ukraine-blames-russia-a...

https://press.un.org/en/2022/sc15023.doc.htm

https://www.amnesty.org/en/latest/news/2022/09/russia-filtra...

https://www.hrw.org/report/2022/09/01/we-had-no-choice/filtr...

About military-to-civilian casualty ratio: again, compare like-for-like. Mariupol is the best analogue for Gaza, and Mariupol suffered tremendous civilian casualties despite not having all that many soldiers in the city. I would be shocked if the ratio was not comparable to Gaza if not worse. Had Kyiv been encircled it would have suffered the same fate or worse.

Even if you use the UN-confirmed deaths in Mariupol (around 2000), which we agree is an undercount, that's around 0.5%, compared to 1.2% in Gaza. On the other hand if it's 10,000, which still might be an undercount, that would be significantly more than Gaza.

But yes, Ukraine has "depth" and a larger population, so yes, lots of the fighting takes place away from cities. That doesn't, of course, prevent Russia from bombing and striking apartment buildings and kindergartens. Like this incident from a few days ago

https://www.youtube.com/watch?v=Mm6j9_XQNtY

Or this one, from yesterday

https://www.reuters.com/world/europe/russian-missile-damages...

But no, geographic reality shouldn't let Russia off the hook. If the conditions were right they'd treat every city like Mariupol, or Grozny.