Your description of Taiwan's response is wrong.
As outlined in [2] I linked to above, Taiwan permitted the docking of the Diamond Princess [1] and allowed passengers to disembark in Keelung (near Taipei), on 31 January, before the ship left for Japan. The ship was subsequently found to have numerous confirmed infections onboard. In reaction, Taiwan's government published the 50 locations where the cruise ship travelers may have visited and asked around 600k citizens who may have been in contact with the tour group to conduct symptom monitoring and self-quarantine if necessary. So at least in the beginning of the pandemic, Taiwan was not closing the doors. Today, Taiwan has essentially the same 14-days entry quarantine as most countries. Another important difference is that Taiwan takes quarantine very seriously and monitored those sent into quarantine via mobile phone location tracking. That too is outlined in [2]. Police will talk to you if mobile phone movements indicate that 14 day quarantine is violated. In contrast, quarantine is de facto voluntary in many European countries.
There is no good reason as far as I can see, why other countries don't adopt similar policies.
I must admit, I am not pleased that I am loosing 1 year of my life because the countries that I live in are not adopting best practises. Indeed, are mostly not even aware of them.
[1] https://en.wikipedia.org/wiki/Diamond_Princess_(ship)
[2] C. Y. Wang, C. Y. Ng, R. H. Brook, Response to COVID-19 in Taiwan: Big Data Analytics, New Technology, and Proactive Testing, https://jamanetwork.com/journals/jama/fullarticle/2762689