here in Germany commercial cold calling carries fines of tens of thousands per call and I have received one in 20+ years.
The overwhelming majority of spam is advertisement. Someone by definition cannot advertise themselves without making themselves liable, so just up the penalty beyond the expected value of the spam and it works perfectly well.
Of course presumably chinese models would keep existing and that gets a little weird.
I see comments similar to this about tech issues, and it always reads as if the person is assuming that these illegal tech activities are being done under the jurisdiction of the laws making it illegal. All you need is one jurisdiction that is not under the influence of the country with laws, and you make it impossible to stop these "illegal" activities
This is the same problem with AI bans that are not unilateral. The powerful will leave the tools open for them and their buddies while punishing everyone else.