It seems to me that you know the answer to the first question "do they
make less" because you have quoted the number "$175,000".
The answer to "Why" is more of an economics issue than a value of
their labor issue. It's all supply and demand.
I recently learned that Broadway performers who are middle of the road
(not the star of a show, but having a significant role) make somewhere
in the ballpark of $75,000. Living in NYC, $75,000 isn't a large
amount and yet these are almost the best of the best in the acting
field. It clearly takes alot of training and tremendous tallent to
get where these people are. Why do they earn so little compared to
say a Laborist or a computer programmer? It's because there are a lot
of people who would love to be actors on Broadway and not a lot of
positions available. I even know some people (very talented people)
who would pay to perform on Broadway. Supply and Demand.
When it comes to Laborists and Hospitalists, I don't even know what
they do but I can tell you that the salary is based on supply and
demand. How many laborists are needed vs how many people want to (are
willing to) go into that career.
There may be more barriers to entry into the field such as the
training/education required, certifications, skill, experience in
similar work... these things may reduce the demand for either
Hospitalist or Laborer positions.