This is probably a typical case of legislation not catching up quickly with the rate of change in technology. In a long time to come, promotion of products and services will continue to flourish on sms etc. But there is a need to provide additional information eg via a link to the business’ website where the details ( terms & conditions governing the promotion etc ) would be detailed.

If the subscriber does not bother to read the T&Cs, then that’s when “they can have themselves to blame”