I can't find this having been addressed before, but it must have been....surely! Given that many, many riders fail to cancel their turn indicators, which can be dangerous, what would be the reason for 'bike manufacturers not incorporating an audible warning device, in addition to the flashing indicator light right in front of the rider which so many fail to see or grasp the significance of?

Perhaps the manufacturers assume that if the rider is blind to the flashing warning light, he/she would probably be deaf as well. It cannot be a matter of cost surely. Could it?

The Lifan 200 Cross comes with audible turn signals. The first thing everyone does is disable them. I remember when I rented a scooter years ago which had this feature. A bit embarrassing sitting at a junction waiting to turn with that thing beeping and everyone staring.

I bought some device for a Wave, when stopped at the lights this thing sounded like a fog horn, was fine if you forgot to cancel your turnsignal when going along. After a while I put tape over the holes where the sound came out and it was much more acceptable when stopped at lights but then couldn't hear it when going along.