On the other other hand, I think the West has not really been involved in this type of warfare since WWII/Korea, so we don't really have a point of comparison with Western tactics.
I should know better than trying to discuss this sort of topic as it's obviously always impossible.
It is also plausible that some residents would prefer to go east to west. Not every resident of Eastern Ukraine supports the government. And we don't hear about it much, but reprisals and extra judicial killings of "collaborators" are happening.
Finally there is self interest. It's by no means certain that refugees who go west will be able to return to Mariupol after the war.
This will all get me voted down because it doesn't suit the narrative. I don't like the Russian invasion and I want it to fail but I also wish we were interested in the truth more than "winning the information war".
What's different is that it is widely publicised pretty much live and that it hasn't happened in some time (although in the Syrian civil war Aleppo was similarly flattened). The invasion of Iraq is a bit different in that the gap between Iraqi and US capabilities was so great that the US did not really need to go all the way on that occasion (and of course they didn't want to show you, anyway).