That’s because of the model. Bike sharing is spontaneous, unplanned. People who are planning on riding a bike will bring their own bike and helmet.
But to require a helmet to use a bike rental service means planning ahead and bringing a helmet. If a person was planning ahead they would use their own bike.
Helmets, bells, hand signals are BS attempts at making cycling safe. It blames the victims in the event of an accident. If you get badly injured by an SUV it’s because you didn’t have a helmet and didn’t tell the driver you were stopping. It’s not their fault
I have 3 sources. Heat pump, oil furnace, and oven.