I would have to agree with /u/danimal88's analysis that it's probably more about market than difficulty. For humans, spoken fluency in Chinese is not nearly as difficult as it's made out to be until you add written Chinese. Voice to text in Chinese is very close to perfect. I suspect that it's actually easier for machines to interpret than English, considering the fact that English is so damned inconsistent in pronunciation, grammar, and phonemes.
Unless you limit yourself to the official dialect of Mandarin, Chinese also has lots of inconsistencies, partially because the majority of the population being able to speak Mandarin is actually a fairly recent development. A large minority has trouble distinguishing retroflex consonants from alveolars. Not everyone's tones have the same pitch contours. Some dialects also mess with the grammar, e.g. by tacking certain parts of speech onto the end of a sentence. So if you want to capture the full variation of the language as it's actually spoken, you'll have similar difficulties as with English.
I would definitely limit it to the official dialect of Mandarin. Consider that French and Italian are both supported by Google Assistant and they have a lexical similarity of .89, which is high enough to be considered dialects of each other [0]. Meanwhile a high estimate of Cantonese and Mandarin lexical similarity pegs it at .62 [1]. I think it's fair to treat support for Chinese "dialects" as different languages.
I suspect the only reason Chinese is categorized as a single language is ignorance and Eurocentrism. German and English have roughly the same lexical similarity as Cantonese and Mandarin, for example. Considering Chinese one monolithic language is like considering all European languages dialects of "European."
> I suspect the only reason Chinese is categorized as a single language is ignorance and Eurocentrism.
Ignorance, perhaps, but not necessarily Eurocentrism. Viewing Chinese as a single language – often with Mandarin as a prestige "dialect" of it – is a common position of Han nationalists.
Attempts by some Western linguists to treat the Chinese varieties in a way that emphasizes their mutual unintelligibility and downplays the importance of the common writing system, have even been attacked by said Chinese nationalists as being "anti-China". It is very similar to how, decades ago, many Russians bristled at attempts by foreign scholars to view Ukrainian as a language in its own right, since their position was that Ukrainian and Belarusian are simply some aberrant or low-prestige forms of the Russian language.
I wasn't talking about Mandarin and Cantonese as "dialects", I was talking about different dialects of Mandarin as spoken in Beijing (which the official dialect is based on) versus e.g. Sichuan. Those are mutually intelligible similar to the varieties of English, but they are markedly different in details of their pronunciation, word choice, and occasionally grammar. European languages aren't the only ones with hard-to-understand regional dialects.
That makes sense, but I don't see why this is any more of a barrier to adopting Chinese than it is for any other language - like you said, European or Romance languages have difficult regional dialects, but somehow they're widely supported by Google Assistant.
"Unless you limit yourself to the official dialect of English, Indo-Germanic also has lots of inconsistencies, partially because of the majority of the population being able to speak English is actually a fairly recent development..."
Just saying, unless you talk about written Chinese, the big languages in China are not even intelligible amongst each other - less so than English, French or German. They are not dialects that can be trained together, they are very very distinct languages. (Of course official CCP-speak says the opposite, but they have never been fans of facts.)
I hope my other reply further downstream makes it clear that I did not mean my comment as you interpret and you just didn't see it.
But just in case, I want to make clear that by "the official dialect of Mandarin", I meant the one dialect of the Mandarin language that is officially recognized by the CCP. Whereas by "Chinese" I meant the language spoken by almost everyone in China nowadays, i.e. Mandarin (I did that because I was replying to a comment that was talking about Chinese, so I used their wording).
Thus, with a correct understanding of my intentions, the equivalent for English would be "Unless you limit yourself to the official dialect of British English, English also has lots of inconsistencies ..." (where the official dialect would be the Received Pronunciation).
