I remember reading this article on the subject and finding it interesting: https://archive.ph/8xyWx

My terrible summary of that article is that it's really hard to turn cell goop into something that is recognizably hamburger. There's a shitload of structure to meat so you have to make the cells do their "turn into this part of a cow" thing. That's been really difficult to scale up. One shortcut you can take is to use actual animal meat as a starter, but then you're no longer making vegetarian meat, and I seem to recall there being some other issue with that.

I really want lab grown meat to work, but I'm losing hope.