Scale Issues. Heights, Mass and Cameras

I’m very into creating realistic simulations in Unity with first person cameras. I find the arbitrary scaling often used creates a big mess. I have read that 1 unit is 1 meter. How is mass measured? If I wanted a human character to behave naturally, then the mass has to be about 75 kilos. How do you set that?

Also, when you scale cameras, it seems to just make them seem shorter or taller in the environment. So the only solution I’ve found to make the camera render things looking correct scale, is to scale everything up in the environment to match the camera’s default size.
Example problem. I create a car sim, and if I don’t scale the entire environment and cars up to correct “meters” the camera will render them looking small, like toys. It’s important for me to have the scale seem real sized.

Mass is arbitrary. You decide what one unit represents. It could be a KG, Lbs, Tons…

As a general rule you should not have masses that are more than 100 times different than other objects.

As for getting you camera to look the way you like involves tweaking the field of view. Scaling the camera’s transform does nothing.