Joli,
That may have worked in an era when cities had populations of just a couple of thousand - small towns in modern terms.
But Kyiv has a population of 3m. How long do you think i5 would take to evacuate and who do you think could build the tent cities and bring in the food, water, field hospitals to support them?
Maybe they think they could just keep walking down the highway to the Polish border lying down and dying at the roadside?