Probably Samsung doesn’t permit it because they don’t see the market.
Taiwan government tries to have a free and open market and Samsung can probably do it if they meet the requirements.
Samsung chooses to sell their tablets and phones in Taiwan but not computers.
Even if Samsung sold computers here they’re barely going to impact the market. Taiwanese just won’t buy them.
There are lots of things you can’t find in Taiwan. And not because Taiwan doesn’t permit it, because the seller doesn’t want to do it.