Although speed bumps are more effective than traffic cameras, the DC government prefers traffic cameras because they are money-grabbing.
With speed bumps, the driver must slow down; otherwise, his/her car will suffer damage.
Drivers from Maryland or Virginia don’t care about traffic cameras because they ignore the tickets, and nothing happens, but with speed bumps and cushions, if speeding, they will suffer car damage.
"In terms of the percentage accident reduction, however, engineering schemes incorporating vertical deflections (such as speed humps or cushions) offer the largest benefits: at 44%, the average reduction in personal injury accidents attributable to such schemes, is twice that at sites where safety cameras were used to control speeds (22%) and they were the only type of scheme to have a significant impact on fatal and serious accidents."
https://www.researchgate.net/publication/7854...emes_on_30_mph_roads
In DC, the use of speed cameras is not about safety, but the money they generate.