There are as said, random road events, plus npc's crashing (quite regular for me anyway), which means keeping an eye on traffic suddenly stopping.
I don't use the pedestrians, just not worth it, looks bad. My imagination can fill in the blanks.
A player can choose to have a large haulage empire or just go solo. I go solo, because it is a relaxing game, but relaxing to a point..

I did the haulage business a few years back and didn't enjoy it much. I prefer just to go it alone.
Weather is random, but no snow in the vanilla game, but there are a couple of really nice winter mods, I would recommend these for every now and then. These mods replace rain with snow, it doesn't build up though, the snow on the ground remains the same all the time. Try setting the route to small roads, for imagination sake, for example there was a diversion, this can make the game very interesting.
Further to the winter mods, one changes traction, which makes it more difficult to drive, so quite realistic. However it doesn't seem to effect the npc's, so they go dashing by while your skidding all over the place, so you have to forgive that.
To add to that: suspension, brakes, weather etc can be altered in the menu. However I would recommend a physics mod for the truck itself, plus a sound mod and also a truck speed/weight mod for npc trucks. Mods:
Advanced Physic's
Sound fixes
TT AI truck speed
Sisl interior bits
Jazzycats vehicles
Also there are weight mods which will give you set weights ie; 50, 60 80ton etc. I use a 50ton at the moment, with the truck physics mod, it works nicely.