Part of that is due to the industry -- they sell multifunction, mini-battery units that a cyclist has to push the switch a dozen times for the needed selection (sure, it's a bicycyle -- give them more to 'cycle' through); worse, these type of lights each have their own switch. Try using these in traffic.I walked throughout most of the past year because I didn't have a bicycle wired up with proper lighting (for night travel).
That wouldn't worry the cyclists around here. Very few cyclists have working lights nowadays. They seem to be above the law as the police do nothing about it.
Although driving manuals still inform about hand signals, few seem to know or heed them. I haven't wired in a stop lamp on the current bicycle (did so on the one that was smashed) but I utilized some small 3v emergency flashers by modifying the printed circuit (added a power line resistor and inserted input wires, etc.). They're connected through a modified main light switch's power lamp so flashing is indicated when either left and/or right directional flasher is engaged. Each directional flasher has one mode and has its own switch located close to the respective thumb. Currently, the tail light is only on with the headlamp. My old system had a seperate switch for the headlamp, so the running lamps (front and tail) could be on when walking a sidewalk, or stopped aside the road.
Sorry about the technical spew but now you know what someone needs to go through; the main point is that the (somewhat) readily available 'multi-function' units are RIDICULOUS on a vulnerable, balance-dependable vehicle where hands-on-the-handles are a necessity.
8-)