When I hear of people in the USA not wanting to work w/ a distributed team based in Vietnam, the most common reason given is timezone. Specifically the need for significant overlapping between the 2 teams.
It is a valid reason. Except for the significant part. My experience running Black Gibbon over the past few years is 30 mins (at the end of day PST time) is sufficient. During this time, a daily standup can be organized, where:
That is it. No more. No less. Anything else can be done asynchronously using email, chat, project management software, bug reporting tools (having a good QA/QC process is critical by the way), Github/Gitlab, design docs.
When I was working for Boston Consulting Group Digital Ventures (Manhattan Beach), we also limited meetings. Most days of the weeks go by where team members have just 1 short call a day. And we were in the same office.
Even when I am in the USA (PST timezone), I make sure to limit calls w/ my USA clients to no more than twice a day.
It is a new world (accelerated by Covid-19 pandemic). Talents are everywhere. If you have the right process, you can make it work very well.