There are commercial machines, but it's important to understand that in the textile industry there's a big difference between commercial and domestic machines, and it's not necessarily that commercial machines are better.
Besides the enormous price difference, commercial machines are usually less flexible than domestic machines. They're optimized to perform a single task at production volume, rather than to do a variety of tasks. Much like how commercial sewing machines typically perform only a single stitch (as opposed to domestic machines, of which modern examples can perform an arbitrary number under computer control), commercial knitting machines can usually only perform a single type of knit. This does mean that the decline of domestic machines in some parts of the textile industry leads to a loss of capabilities that used to be available.
Besides the enormous price difference, commercial machines are usually less flexible than domestic machines. They're optimized to perform a single task at production volume, rather than to do a variety of tasks. Much like how commercial sewing machines typically perform only a single stitch (as opposed to domestic machines, of which modern examples can perform an arbitrary number under computer control), commercial knitting machines can usually only perform a single type of knit. This does mean that the decline of domestic machines in some parts of the textile industry leads to a loss of capabilities that used to be available.