> From a quick search, it looks like national accents are less of a problem, and the real difficulties like in dialects and foreign accents (e.g. a Spanish person speaking English).

Can confirm, in high school I had to occasionally go AFK after being beckoned talk to the amazon echo because it wouldn't understand my parents' accents.

A lot of immigrant children get used to translating for their parents, but repeating commands but with a native accent is a newer phenomenon.