How do modern cars regulate temperature so well?

200°F is not hot. Neither is 205°F. My Contour electric fans are set to keep my Duster between 200°F and 210°F, and really that's lower than it needs to be.

Remember what the stock thermostat on these cars was? It's a 195° F. You think they ran everywhere at 200°F? They did not. And most of the factory gauges do not have actual temperatures on them, so they're no better than a new car. Probably less accurate too.
I won't argue about it. You can hit the disagree all you want, but when I sit in a drive through on a hot summer day, my temp gage doesn't move but the electric fans will kick on at a certain temp. That tells me the engine temp raised but the gage did not. It's true in the newer Dodge mini vans, my 'stang, etc. Also, I don't care where others chose to run their cars for temp. Mid 70's Shop Manual states 190* stat is standard equipment, and that is to ensure you have a Happy Heater in the Winter and emissions, not because it's where the car is the happiest. Again, I couldn't care less what anyone runs their temp at, I'll run mine on the cool side.