Honestly I had zero interest in this show - having not particularly liked Discovery or Tilly herself - but with the addition of the Doctor and Tig I’m now feeling the hype! I’ll definitely check it out.

That’s also Vegas but with mafia instead of slaves

If I had to guess the answer would be time and land usage. A single humidity and temperature controlled facility could likely produce huge amounts of densely packed mycelial wood substitute compared to a huge forestry area that takes many years.