In fact, your point brings out a comparison that hadn't occurred to me. In the West, people tended to draw a line between their countrymen on one side and foreigners or colonial subjects on the other. Behavior that was taboo against one's own countrymen was acceptable when applied to those on the other side of the line.
Well, I still think that what the Tsarist Government did on Bloody Sunday (gunning down recalcitrant workers, students, etc.) was nothing new, either then or today, western nation or non-western nation. Look at the Ludlow Massacre in Colorado in 1914 -- National Guardsman gunned down 66 striking coal miners and their families. Nobody was ever prosecuted. True, the killings didn't take place on the steps of the US Capitol, but nevertheless, the government was treating these workers as enemies, right? They weren't foreigners or colonial subjects.
However, I still find it inconceivable that one of the major western powers would have fired on a peaceful crowd in the center of its capital city.
Look at the Paris Commune. The French Army slaughtered between 17,000 and 30,000 people in one week. They weren't foreigners or colonial subjects; they were fellow Frenchmen and women and children -- they were the citizens of Paris who had had it with a bad government that foolishly got them mixed up in a war with Germany. And this happened a mere 34 years before Bloody Sunday.
Here's another example; On October 2, 1968 Mexican troops mowed down 300 to 500 unarmed students in Mexico City's Plaza de las Tres Culturas.
And, of course there's Tiananmen Square which isn't in a western country, however.
What happened on Bloody Sunday was a sick, vile act against innocent people. But I think Bloody Sunday could happen in any country.
I do agree with you completely, Tsarfan, that it was massacres like Bloody Sunday which led to the massacre in the Ipatiev House.