“SMS has a field called sender ID, which is set by the sender, requires no identity verification, and can be any arbitrary short string.”
Anyone can send a text that says it comes from your bank. Your phone files it in the same thread as the real messages from your bank. Carriers could tie sender IDs to verified numbers, and some countries already do. Banks could stop sending links by SMS. Neither wants to pay for it, so the user eats the fraud.