If you look at your negatives you will see that they are almost blank in the areas that correspond to the dark and green parts of your prints.
Blank parts of negatives mean that not enough light got to them to allow the detail you like to be recorded there. In other words, they were under-exposed.
The under-exposure most likely resulted from your camera meter reading the sky instead of reading mostly the ground with a little bit of sky mixed in. Shots with a lot of sky often end up fooling meters, unless you watch for that.
With respect to the negatives you have, a custom print, properly done by a skilled individual would most likely show very dark and detail free shadows in those almost clear areas. The lighter areas in the scene would be lighter than that, but still disappointingly not bright.
The custom print would get the colour closer to right though.
Your prints, and the scans that they were most likely made from, reflect the fact that they were almost certainly made using automatic machines. When those machines encounter a severely under-exposed negative, they struggle mightily to extract as much from it as they can find, even if there isn't much there to extract.
Those automatic, best they can do efforts usually result in something pale and discoloured.
If you give the film more exposure, the automatic systems in the scanners and printers have something to work with, and usually do a better job.
Welcome to Photrio. Hope this is some help.
