Got a source for that? I've never been involved in commercial vegetable farming or large-scale cattle raising, but small-scale ranching is really not that labor intensive in my experience.

Animals don't eat vegetables. They eat hay and grains that can be dry land farmed on undesirable land with minimal labor.

Crop labor has also seen a lot more automation in general than meat labor over the last several decades. Some crop farms are almost entirely automated (and International Harvester and other brands think that Level 3 self-driving tech alone puts them on a path to nearly full automation in the next decade or so), though obviously things vary based on which crop.

On the other hand, slaughterhouses generally haven't seen any automation and other than size/scale mostly still resemble their counterparts from previous centuries.