In the days of incandescent lamps the power of headlights, sidelights and brake lights were set, by law, to limit the maximum intensity of light emitted. Now, with modern light technology, the light output is many times greater. As far as I am aware, the law hasn't changed and power is still the legal requirement. This has led to lights getting brighter and brighter.
With modern vehicle instruments being illuminated whenever the ignition is turned on, and bright DRLs fitted to vehicles, I often see motorist driving, in town and after dark, with no lights to the rear, mistakenly believing their lights are on. In the "old days" your first look at the speedometer showed you that all was dark, and the mistake was quickly rectified!