BS. Many countries have successfully implemented SMS sender registration/verification schemes. See for example here for a list: https://support.sms.to/support/solutions/articles/4300056265...

The details differ per country, but either all non-registered senderids will be blocked, or registered senderids will be allowed only from authorized sources. The degree of mandatoriness varies also, in some places its mandatory for telcos to comply, in other places it is some voluntary cooperative scheme.

But despite such details, the problem is clearly not completely intractable.