I've already said that, but my cousin (emergency care) in Colmar was sending his "best" patients in army planes to another cousin working in Brittany (reanimation). He worked 12 to 14 hours a day, for 45 days straight. That was one hotspot, and Colmar was hit a bit less than Bergame, i'm pretty sure any italian having familly there would have many more horror story than i have. At least they didn't have to select patients in Colmar (well, not as much).
I'm not sure if the difference from the European countries is in people complying or with good implementation (clear, short rules). Either way, spread inside the city (so the island / sparse pop arguments are irrelevant) has been eliminated.
The difference in rules simplicity and exclusions is visible. Compare for example official rules for UK's level 3 only https://www.gov.uk/guidance/tier-3-very-high-alert with Victoria's 3 steps all together on this page https://www.health.gov.au/resources/publications/3-step-fram...
I'm in Sweden at the moment and I've essentially locked myself down, even though its not legally required.
In that sense, it "works". Whether it's worth the cost is another issue, but it does sound like certain hospitals were filling up rapidly.
The strongest evidence I've seen is China. It was the center of this pandemic and now the virus there is basically gone. Sure they lie about their numbers and there probably some community spread here and there but there's no way they are completely hiding a pandemic.