Yeah, just uses/abuses Opticom—the same Fire/Ambulance/Police override that many traffic lights already have installed.
Crucially—since it is easy to jump to conclusions—it is not a full hostile takeover of the PLC controlling the lights. You can't make a dangerous "all green" scenario here; it's just using an restricted-access feature that's basically security through obscurity.
Though, the idea that someone can be prosecuted because they can cycle IR LEDs at 14 Hz—the rate of an Opticom—is just hilariously dumb. Pick a more secure, authenticated protocol!
Yea, but this is the most cost effective and economical solution. Managing encrption/auth keys down to distributing it to multiple LEO, FD agencies, and multiple public and private EMS vehicles isn't a simple task and would quickly grow to needing to permanently contract a vendor to manage it which will come at some blood sucking premium.
Instead, the good ol' pipe wrench approach works great here, the emergency services get their IR light that any garage in town can install, and anyone that tries to abuse it gets a free fine or prison sentence.
Though they aren't going to throw you in prison because you you had IR leds at 14HZ. They will if you used them on a vehicle, pointed at traffic lights because your intent was interference with a traffic control device.
