Just of the top of my head here are some possible ideas to explain why not:

• Meat subsidies
• Meat substitutes require more processing and additional ingredients
• Meat sells a lot more than meat substitutes hence the whole chain benefits more from economies of scale
• Animals raised for meat can extract nutrition from plants and parts of plants which humans cannot (for example cattle can actually break up the fiber in food and extract nutrition from it, which humans cannot), plus they can eat plants which are far more hardy than most plants grown for human consumption. Some will also eat other animals which humans do not, such as insects.

I doubt it's just one of those things that is responsible and suspect it's a mix of those and maybe more.

This is correct, however:

You need to also take into account that plants are just the primary ingredients and it needs a lot of intermediary steps during manufacturing.

I say this not to say you're incorrect but just to be a more complete picture so it's unassailable

Meat and dairy are heavily subsidised

I can chime in here (I work in plant based meat). It should be but it's not. Why... Lots of reasons. But basicly it's split between animal based meat is artificially cheap and plant based meat costs a lot to make. A lot of the costs (for the good brands) are in the flavorings.

what are you on about? don't you know it's far cheaper to grow a bunch of plants and then feed it to an animal for a long period of time while that animal grows and then harvest that animal for a small portion of the calories it consumed?

If it is the same process I saw years ago they extract something from vegetables that is what gives blood its color and taste, and that is the the sauce that make it taste like meat, and that process, I guess, is expensive at least in part because plants have very little of this compound.