Nitpick: "are actually purple" makes it sound like they came out of the factory purple, but they're actually changing from white to purple over time as the phosphor coating fails.
They'll be near-UV LEDs with a phosphor to produce white, high efficiency, low cost, but garbage long term.
The city employee who bought them is probably a massive Ravens fan...
i mean who wouldn't be the way they're playing
Might be so that they don't interfere with a certain species of wildlife. We have deep blue ones near me that aren't visible by a protected bat species.
They’re purple (blue is the other option) because veins are harder to see under purple light. They’re used to deter drug use, from my understanding.
Edit: final clause
Not true, they're just defective and degraded quickly, resulting in the odd color.