I think most of these comments are from really technical people doing really good international work and are annoyed when they see other good people make some minor errors. Most of these complaints seem based on experiences from the best-of-the-best with regards to international support. My list is more basic. This is what all developers, not just Americans, should do:
1) Use Unicode. It is 2017, please stop using Windows code pages. Please use software that at least supports Unicode. Americans aren't the worst culprits here.
2) This one is for the Americans - don't assume all countries have US-style addresses. Just changing "state" to "state/province" and "zip code" to "postal code" is not adequate.
3) For you GIS people, don't assume all countries have a strict US-style administrative boundary hierarchy. Even the US doesn't have the administrative boundaries you think it does.
4) Again for your GIS people, please review point 1 above.
5) For you "data scientists", please review point 1 above. Don't just change your original data to make it ASCII. And if you do, don't give the result to the GIS people to geocode.
6) For other "researchers", please don't refer to these characters are "junk" or "garbage data" in meetings or presentations. You are offending both non-English speakers and people who speak both English and Unicode.
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