One of the problems is that the link shown in the text message masks the URL of the duplicitous website. This is in contrast to desktop browsers, where you can see the destination URL of the link text in the browser status bar before you click on the link. In a text message, this is not possible.
People tap the link in the text message which opens the link in their mobile browser. Few people, I suspect, look at the URL in the browser address bar. And if they do, the small size of the browser address bar will show only a portion of the URL - the portion of a URL that may not arouse suspicion.
Another question: how do these scammers get mobile numbers? I suspect there are many online personal data breaches which are never reported e.g. a breach from an online retailer, or maybe a friend with your contact details who has been hacked.