These are not playoff systems for a championship but for a promotion/relegation

And again, UEFA CL is NOT (look that up if it is confusing) single country league. Once Chiefs start playing Montreal Destroyers and San Salvador Bulldogs in North America Football league than we can compare US sports leagues with UEFA CL. until then, try to find a country in which there are playoffs after league season is over, only US does this garbage and makes regular season generally un-watchable and meaningless