I don't think 'healthy' meant no meat there, it was just about (lack of) fast food (whether it be meat or not, but mostly is).
Depends on the meat and its alternative. Later is always better for the environment
Why does it cost more then?
Because it’s newer and externalities exist?
I'm assuming it is because of the lower volume of alternative burgers. Looking at my supermarket, they have probably 150-200 linear feet dedicated to meat and maybe 5-10 for alternatives.
Meat is heavily subsidized.
Subsidies. I'll just link my other comment from this thread.