Labor Intensive

Something that requires a lot of work. Like, lots of people putting in lots of time to get a job done. Building a medieval cathedral was a labor intensive operation. People carrying bricks by hand up ladders and scaffolds...the pulley considered a new-fangled invention that no one over 25 (middle age at the time) could figure out how to work.

You can tell you are involved in a labor intensive operation if a large portion of your costs are related to labor. Otherwise, it might be a capital intensive operation...one that doesn't require a lot of people, but does rely on expensive machines.

If you operate your own private subway, that's a capital intensive business, but not labor intensive. Once the tunnel is dug and you buy the train, the only labor is the driver. Not too expensive, relatively speaking. However, there's significant expense in running and maintaining the train.

Now, digging the original tunnel may or may not have been a labor intensive operation. If you and your buddies dug the subway tunnel on weekends using store-bought shovels, then...yeah, pretty labor intensive. But if you used a large drilling device, like the kind used by Superman villains, then the process again becomes more capital intensive.