Earlier quoted context omitted.
As a cyclist it's often helpful to be able to hear the sound made by cars moving across a street, for example, when approaching an intersection where perpendicular traffic should stop, but may not.
As a casual slow cyclist myself I already find it impossible to rely on audio too Mich, visuals are always needed. I have had several near collisions with other cyclists in the past who silently sneak up from behind or around corners. Afterwards I made sure to always look around before changing direction and treat every obscured corner as potential "devil puppet on a spring box" (no idea what they are called :) ). I…
When I worked with deaf people as relay operator, a question asked by a coworker during our orientation session on deaf culture was 'How do deaf people drive if they can't hear sirens from emergency vehicles?' The answer is that they rely on their other input to and have learned to compensate for their lack of hearing. In effect they may be aware of these possibilities and check their rearviews more frequently to account for not being able to depend on auditory updates.
If all vehicles were completely silent, it would remove the benefit those of us with hearing gain from the additional input, even though this input isn't strictly speaking necessary. We could and would adapt, sure, but I think that additional factor when cycling does help in some situations. I can see engines making some noise to be advantageous, even if it only makes the difference of one fatality a year, because there is very little drawback.