You directly tied vaccines, supermarkets, and computers to "massive, organized economies" and tied that to Capitalism, so if I misunderstood what you meant by that then fair enough. However, what follows in your comment is not evidence for belief in superiority of one economic system over the other.
Your first major paragraph talks about how, in your vision, highly developed countries tend to be Capitalist, while despite the obvious benefits of Worker Co-operatives, they seem to be rare in these developed countries. I'll answer each bit individually.
Capitalism is a system of exploitation, whereby owners suck up the value workers create. As the world gets increasingly complex, the farther away from the top you are, the more exploited you are. In the modern era, this expresses in totally imperialist control of the global south. Nestle, for example, uses child labor and brutal working conditions to extract necessary resources and profit immensely, despite being headquartered in Nordic Countries, where the quality of life and development are some of the highest in the world. This is by no means an exception, it's the rule.
What drives quality of life is not what economic system you have, but the level of development, largely. Reducing disparity is fantastic as well, but primarily, development determines quality of life. Tying supermarkets, vaccines, and computers to Capitalism, rather than to developed nations, is a bit of a misattribution: The tools and goods present in a country do not care who owns tools, all they care about is investment in industrialization and development.
As for why Worker Co-operatives are not more common, it's fairly simple. Despite being more stable than Capitalist entities, and providing greater worker satisfaction, Co-operatives are more difficult to start than Capitalist entities. As we have previously discussed, it is in Capitalist's interest to keep it that way, and prevent the system from incentivizing these better structures, so that they can maintain power.
Next up, your request for a "specific example" at a country-scale of what I am asking for. The shortest answer is that there isn't one, at least not yet, but that by no means discounts the possibility of its existence in the future, you'd have to explain why you think it impossible. The longer answer is that there have been several examples with radically different structures that modern leftists have all learned from, but none of which were 1 to 1 what leftists seek to replicate. What do I mean? Well, some examples include the EZLN and Revolutionary Catalonia, which are/were Libertarian Socialist and Anarcho-Communist, respectively. They have their own shortcomings, notably the modern lack of existence of Revolutionary Catalonia due to its inability to defend itself, and the EZLN for being very slow at developing, though it works for the people who live there.
There are other examples of more statist countries, organized along the lines of Marxism-Leninism. These include places like Cuba, the USSR, and China. While the latter 2 did manage to skyrocket quality of life with huge investments into development, ultimately the Politburo is unaccountable to the masses, and as such the governments of each have committed atrocities. Cuba is a bit of a unique case, it's nearly completely locked out of global trade, and as such it has had severely stunted development.
So far, I wish to recreate none of those examples, but each has provided extremely valuable information on how to build a future Socialist society. You appear to be rejecting the idea of analyzing the mechanics of Socialism and Capitalism and applying the results of that analysis to the real world, and instead you appear to be in favor of simply "copying whatever country has a higher quality of life," without looking at trends or cost. Again, leftist believe that Capitalism itself is unsustainable and brutal, and therefore needs to be replaced with Socialism. This is not because of vibes, but genuine mechanical analysis.
I have a question for you, if you'll oblige: what is the extent to which you have read leftist theoretical texts, such as from Marx, or even Anarchists like Kropotkin? If none, would you be willing to read?