> In some places, criminals are killed much more quickly as punishment. Should we do that instead, because some countries do it?

You do. USA is a world leader in killing criminals. Only China, Iran, Saudi Arabia, and Egypt kill more per year.

> Or maybe we should figure out what we want to do by argument and consensus, instead of blindly following the old colonialists and ex-fascists in Europe?

You don't do that. You blindly follow some 20yr old colonials who scribbled out a constitution 200 years ago.