This whole thread has a bunch of answers which are confusing the topic.
The issue is why would Taiwanese businesses care about the China market? Aside from the fact that the China market is massive, there is a simple answer: Taiwan and China have the same business language, and that is Standard Chinese aka Mandarin.
Yes, lots of Taiwanese people also speak other Sinitic languages that are not Mandarin, and are not mutually intelligible with it. And lots of Chinese people also speak other Sinitic languages that are not Mandarin and are not mutually intelligible with it. And even some variants of Mandarin itself are not mutually intelligible. But - outside of Cantonese in HK and Macau - none of those languages are used as the primary business language anywhere in either China or Taiwan, so it's an interesting side note but doesn't change the point.
All that said, aside from the Chinese market being massive, and the common language being convenient, there is a much bigger elephant in the room that explains why Taiwanese companies might not have a fun time doing business in China: politics.
It doesn't matter how much money Taiwanese companies might want to make if the CCP can threaten to turn off the spigot any time they want to influence Taiwanese politics, which unfortunately nowadays appears to be all the time. Sure, it's leaving a lot of money on the table, but doing business with Japan or the US or other countries that aren't run as a single party dictatorship whose leadership has a stated platform of dismantling your own government might be a less risky option.
> none of those languages are used as the primary business language anywhere in either China or Taiwan
我同意。
I was just trying to dig into what OP meant by "Taiwanese" as a language.
It's always going to be Mandarin for anything commercial.
That said, you can't deny the benefit the Hakka and Hokkien diaspora provided to China's manufacturing capacity - it was diaspora Chinese from Thailand (CP Group was the first foreign private company to incorporate in China), Malaysia, Singapore, Indonesia, and Taiwan had on PRC's catchup.
In Taiwan it’s called Taiwanese. It’s similar to Hokkien which is why it’s often referred to as Taiwanese Hokkien. But it’s not 1:1. And people outside of Taipei will assume you speak it and understand it.
The issue is why would Taiwanese businesses care about the China market? Aside from the fact that the China market is massive, there is a simple answer: Taiwan and China have the same business language, and that is Standard Chinese aka Mandarin.
Yes, lots of Taiwanese people also speak other Sinitic languages that are not Mandarin, and are not mutually intelligible with it. And lots of Chinese people also speak other Sinitic languages that are not Mandarin and are not mutually intelligible with it. And even some variants of Mandarin itself are not mutually intelligible. But - outside of Cantonese in HK and Macau - none of those languages are used as the primary business language anywhere in either China or Taiwan, so it's an interesting side note but doesn't change the point.
All that said, aside from the Chinese market being massive, and the common language being convenient, there is a much bigger elephant in the room that explains why Taiwanese companies might not have a fun time doing business in China: politics.
It doesn't matter how much money Taiwanese companies might want to make if the CCP can threaten to turn off the spigot any time they want to influence Taiwanese politics, which unfortunately nowadays appears to be all the time. Sure, it's leaving a lot of money on the table, but doing business with Japan or the US or other countries that aren't run as a single party dictatorship whose leadership has a stated platform of dismantling your own government might be a less risky option.