It is my decision whether your notification is worth my time. If you're using SMS because you don't think that I'll give you push notification permission then that tells you that I literally do not want them (save your monthly fees too :) ).
That said your concern is incredibly valid and it’s why SMS needs to remain somewhat expensive. Could you imagine if SMS was as cheap as email? Holy shit the spam volume.
I ignore texts from people I don't know (not in my address book).
I am pretty solidly in camp A, I will read every text message that hits my phone but if it's spam or something like that I will just get pissed off and remember not to give that company/person any money ever. But I still read it.