Legally, use of horns in traffic is restricted, and abuse can be punished. Doesn’t keep people from honking all the time.
Tho I like the proposal to require that manufacturers design car horns to sound as loudly inside the cabin as outside. Might make a dent.
I myself pretty much never honk. I understand honking makes sense on narrow bendy roads like in the mountains, where you need to alert the drivers behind the corner, but I don't see any other legitimate reasons to be honest.
And now you want to take that away too? No thanks. I get safety is important, but so is relief from noise pollution. Noise pollution is very damaging to your health. There needs to be a balance, and currently the safety police are weighing the scales inappropriately low.
And of course there will always be fringe cases. What if I go to sleep with regular foam earplugs, what if I take a sleeping pill etc. Or what if the warning sound can't be engineered to fit a ANC friendly frequency, like somebody screaming, a car tire screech behind me and so on.
Also ANC works best on wide-spectrum sounds, so any kind of siren or the cries of a child will go through, as the spectrum is a series of narrow peaks.