That is correct. The code requirement for a door protective device was for years just the mechanical contact bumper type. When light ray type devices were introduced and codified, the original requirement was a beam at 6" from the bottom and (I think) 24" from the bottom. With that configuration, it was found that a person in, for instance, a wheelchair could position themselves in the opening in such a way that the light beams actually passed through open spaces in the wheelchair (for instance, through the wheel spokes) is such a way as to render the wheelchair invisible to the light ray door protective device which pretty much guaranteed that the door would smash the wheelchair - and hopefully activate the bumper edge and reopen - otherwise there were unpleasing results.
With the passage of the ADA (Americans With Disabilities Act) the code required all new elevators to have a continuous type of sensing device that operated up to (I think) 72" from the floor.
Elevator companies made a lot of money retrofitting old elevators with the new 'light curtain' devices, especially if the sales department convinced the owner that there was a possible liability if they didn't refurbish (something that the code did not require - old stuff was grandfathered, only new installs were required to meet the new code..)
And speaking of canes and elevators... One day back in the dark ages (or maybe it was the early '70's...) we got a call about someone trapped in an elevator. On arrival in the building you could hear this alarm bell going off. Alarm bells will sound if someone pushes the alarm button, but most people don't do that continuously. Alarm bells will also ring if someone pushes the 'stop' button (note, the newer codes have eliminated the stop button and replaced it with a key operated switch..) and the 'stop' button does exactly that. And rings the alarm. Continuously. Until the stop button is pulled out/restored to its normal position.
Anyway, we found that an older gentleman had entered the elevator, and apparently after the doors closed and the elevator was in motion to some upper floor, the gentleman somehow bumped the stop button with his cane. When the elevator screeched to a halt with this noisy bell continuously ringing, the older gent apparently panicked and started beating the crap out of the interior of the elevator with his crowbar, er, cane. By the time we were able to extricate him, he had broken most of the push-buttons, a panel in the dome (the false ceiling) and dented the crap out of the door panels..
Next time, I’ll take the stairs.
If it was before the common usage of LED devices for lighting tasks, I.E. before the advent of the blue LED, then it can legitimately be considered the dark ages.
I should know.