To be clear, I was not connecting ice "hardness" (hard vs. soft) to quality. I'd say there is a range and sweet-spot, with the extremes in both directions being poor quality. I was only stating that due to the noticeable difference I run a larger hollow in Europe. Figure skating demands softer ice, speed skating harder/faster ice.
My home rink here is mixed use (mostly figure skating, public skating, and hockey) but dedicated indoor arena. The DEL pro practice rink (dedicated hockey year round) is actually bit softer imo. The building and ambient temp. is warmish and humid. Tap water here is very hard (full of "kalk"). Both facilities are top quality. I would never comment they have "bad ice", it's only relatively softer than the Alberta sheets I'm skating on.
I come from north of Red Deer, slightly colder and dryer. There I also skate outdoor pretty regularly. As recently as this January still skating down to -18, although more like -8C to -3C is ideal. Overnight drops -10 degrees colder or more.