On my last train set, I had a fiber optic backdrop that had a literal 6 miles of fiber optic cable in it. I strung every one of those six miles of cable roughly 3 feet at a time.
All of my cars and trucks had working headlights. All of my semis had the correct number of clearance lights and taillights, also done with fiber optics. This was an N scale layout, an average passenger car is the length of a penny.
I hand built 1100 trees. For the bigger ones, I could do nine an hour, the smaller ones I could do twelve. My buildings had interiors, and different furniture in each room, and were also fiber optically lit.
The amount of work it would take to build a set like that is mind blowing.