Stupidly dangerous and (in my country) illegal.

Please retract your comment and don't encourage such stupidity.

EDIT: Since this is being misinterpreted... Earplugs that deaden sound are fine and encouraged on a motorbike, playing music in your ears is what masks other sound and is both stupid and illegal.

Really depends on how they are being worn. If they are on without any sound being played its fine. Ear plugs are highly encouraged while riding a motorcycle and after a decade plus of riding I have never thought ear plugs along with a headset prevented me from hearing whats going on around me.

Maybe it is your own misinterpretation as the parent never said they were playing music on them. You might not realize just how loud the wind noise is on a bike, you are not exactly hearing your surroundings music or not. Most if not all of your awareness on a motorcycle is coming from your eyes not ears, so hard to really say its stupid.

It's been decades since I've ridden motorcyles but as I recall the helmet usually had foam padding over the ears and that was adequate for wind and noise reduction.

Since the advent of EVs, its not a safety issue imo. When Tesla's first came out, and the first adopters were all people that wanted to drive FAST, I was often surprised by them, especially since I always rode slightly faster than traffic as a safety mitigation technique. I quickly learned to use my eyes more.

My eyes are my ears and you cannot rely on sound to know who or what might be coming up from behind you. Mirrors and head on a swivel are way more important.

Deaf people manage to get licenses with no problem. My hearing was never tested to get my license, unlike my eyesight.

Is using headphones on a bike with music on or not somehow different from driving in a Lexus with music on or not?

I wear earplugs and play music via Cardo while riding nearly every single day. It's fine.

Let's be realistic - noise cancelling isn't a perfect technology. I rode with my AirPods for a short period of time and could still hear everything I needed to. The only reason I switched is because they're uncomfortable in a helmet.

My earbuds have a setting to allow for outside noises. Wearing them while walking, I often hear cars and other people well before I see them. Even with louder music, I still hear them. I can hold a conversation with people without taking them out. I don't wear them without music, though, because my own breathing is also louder and irritating.

If I have the noise cancelling turned on, it would be downright unsafe.

While it is likely illegal in many places, it isn't everywhere and the safety risk depends on what sort of equipment you have.

It is not illegal in every country. Further, wind noise and exhaust are too loud to hear anything anyway, so having music on and navigation is a bonus.

If that's illegal than cars with closed windows would be illegal too. Even more so if they have the radio on. As a cyclist I keep having issues with car drivers not hearing anything happening outside of their vehicle (not a bell, not yelling, not a bicycle hooter). That's like wearing headphones or earplugs and still is considered normal. I'd love if everyone would be required to drive a cabrio.

Why stop people from winning Darwin awards?

A lot of motorcyclists are the scum of society in other ways. Probably higher levels of domestic violence than the police.

You want to wear airpods while on the motorcycle? If this is an unironic idea you are having, indulge!